The benefits of reciting Compassion Buddha mantra are infinite, like the limitless sky. Even if one doesn't have much intellectual understanding of Dharma, even if the only thing that you know is Om Mani Padme Hum, still the happiest life is a life lived with an attitude free of the eight worldly concerns.
          If one lives one's life with that pure attitude free of attachment clinging to this life and then just spends one's life chanting Om Mani Padme Hum - this six-syllable mantra that is the essence of all Dharma - that's the purest Dharma. It looks very simple, very easy to recite. But it's not simple when one thinks of the benefits.

                            Here I'm going to mention just the essence of the infinite benefits:

          Reciting this Compassion Buddha mantra one time completely purifies the four defeats of breaking the four root vows of liberation for self [Pratimoksha vows] and purifies the five uninterrupted negative karmas. It is said in the tantra Padmatrawa (rgyud padma trwaba) that it purifies the four root and five uninterrupted, and that all the negative karma without exception get purified. It is also said in the discourse called Exalted Eleven-Faced One: "Bhagawan (Destroyed, Qualified, Gone Beyond), my heart mantra has such great miracle power that by reciting it one time, the four root downfalls of liberation for self are purified." If one recites precisely as explained in the text, there is no question that one gets all these benefits. It is also mentioned in the tantra that one achieves the four qualities of being born in the Amitabha Buddha pure land and other pure lands, at the time of death, one will see Buddha and lights happen in the sky (meaning white light or different colored clouds appear), the devas make offerings, and one never goes to the lower realms [the hell, hungry ghost and animals realms]. One will go to the pure land of Buddha or one will be reborn as a happy migrator being. It is written in the tantra text Padma Chöpen gyi Gyud: "Sons and daughters of the race, anyone who recites the mantra Om Mani Padme Hum while thinking of me, even just one time, or just even remembering or keeping [the mantra] on the body, purifies five uninterrupted negative karmas, the nearing five uninterrupted negative karmas and all the negative karmas and they abandon the eight realms where there is no opportunity to practice Dharma: hell, preta, animal realm and so forth. "One will not experience suffering of body, speech and mind. One will be free from fears of vicious animals, cannibals, human beings, non-human beings and sickness. One will actualize the meaning of Dharmakaya; one will see the holy face of Great Compassion, the rupakaya."
One who recites ten malas a day, if they go into the water to swim, whether into a river, ocean or whatever, the water that touches the person gets blessed. It is said that up to seven generations of that person's descendents won't get reborn in the lower realms - hell, hungry ghost and so forth. The reason for this is that due to the power of mantra, the body is blessed by the person's reciting the mantra and visualizing their body in form of the holy body of Chenrezig. Therefore, the body becomes so powerful, so blessed that this affects the consciousness up to seven generations and has the effect that if one dies with a non-virtuous thought, one is not reborn in lower realm. Also, when such a person who has recited ten malas of Om Mani Padme Hum goes into water - it can be a river or ocean - the water that touches the person's body gets blessed, and then this blessed water purifies all sentient beings, however many billions of billions there are in the water, for example in the ocean. So it's unbelievably beneficial That person who does the meditation and recites the mantra when they go into the water, even to swim or play in the water, saves the animals in that water from the most unbelievable suffering of the lower realms.
If that person is walking in the road and the wind touches that person's body and then goes on to touch insects, their negative karma gets purified and it causes them to have a good rebirth. You have to understand that similarly, when that person does massage and touches others' bodies, the negative karma of those people gets purified. Such a person becomes meaningful to behold; being seen and touched by others all becomes a means to liberate other sentient beings.
If a person who did Nyung-Ne well is on top of a mountain and down below someone else sees that person, their negative karma gets purified. Some of these benefits are mentioned in the tantra Thuk Je Chen po Ton Shak Pe Gyu. So this means that even if the person's breath touches other sentient beings' bodies, their negative karma gets purified. Anybody who drinks the water where such a person swims gets purified.
A very high Amdo Lama, Kungthang Jampelyang, said: "If you are able to request from the heart, even if you do Nyung-Ne for one day and recite the six-syllable mantra, even though you have created the negative karma to be reborn in the hell realm without break and be burned there for years equaling the sand grains of this big earth, even those karmas get purified." This is mentioned in a tantra text that this lama quotes. Kungthang Jampelyang also said: "You have collected limitless negative karma created from beginningless rebirths, and even in this life you may transgress the three vows, collect negative karma with the gurus and with vajra friends, then with the holy objects of the Three Rare Sublime Ones, and carelessly used the polluted food and so forth [food offered by people with devotion or which was offered to the Sangha community by people with faith]. As you are abiding on the precipice of the hell realms, when you meet such Dharma as this, if you do have a mind, then there is no choice. You have to put all your capacity into this practice."
It is also written in the sutra called Samato go pe Do: "If this six-syllable mantra is written by hand on rocks or on stone walls and then men, women, children, daughters, sons and any sentient being touch this mantra with their hand or look at it, just by merely seeing it they become Bodhisattvas of the end of samsara."
In a text composed by the very learned Sera Je Geshe, Geshe Jampa Chodrak: "Thus, by meditating on the holy body of Compassion Buddha just once, hearing the holy name just once or keeping the word memorized or seeing the six-syllable mantra written or just touching it by hand, one gets protected from spirits called De and spirits called Za, which cause paralysis, from Yamas, evil vicious animals, diseases, dangers and harm from human beings and non-human beings, and whatever wishes of this life one has - such as long life, wealth, power and so forth - get fulfilled exactly as wished. Then the five uninterrupted negative karmas and so forth, such as extremely heavy negative karma collected from beginningless time get purified, and one receives good rebirth through all one's future lives and one is able to see Compassion Buddha's holy face and so forth… "If it is said that there are such limitless skies of benefits from remembering the qualities of Arya Compassionate-Eyed One and remembering the kindness and blessings and even just reciting the holy name, then one must attempt to practice, making offerings and requests and so forth." These comments come from a text by Geshe Jampa Chodrak and I also say the same thing.
We are unbelievably fortunate to have met with the Dharma and to have the opportunity to do recitation and meditation on Compassion Buddha. It is so easy to purify whatever negative karma collected, not just in this life, but in past lives. Because we have met the Buddha Dharma, and especially this method, the practice of Compassion Buddha and recitation of the mantra, it is so easy to purify negative karma and collect extensive merit and so it is easy to achieve enlightenment. So we are unbelievably fortunate. Therefore, there is nothing more foolish than not taking advantage when one has this great opportunity.
Normally, one gets distracted continuously, and wastes one's own life. Not only that, but all the actions done with ego and with the three poisonous minds [anger, attachment and ignorance] create negative karma, the cause of suffering. Using this perfect human body to create only suffering - nothing more foolish than this can be found in existence.

There's a tradition to do Compassion Buddha retreat, reciting 100 million Om Mani Padme Hum mantras. It's very common in many places to hold this retreat - in Tibet, Nepal, India and Ladakh. This one at Chenrezig Institute will be the first time such a retreat is held in the West, and the first in the FPMT organization. This is to happen there once each year - only once each year! If you're feeling guilt in your life, by attending this retreat, through purification, you overcome this. The retreat is not just chanting mantras with sadhanas, but also includes taking eight Mahayana precepts, if not every day, at least frequently. That day, whatever merit you collect increases 100,000 times. This becomes such an easy way, a quick way, to purify, collect extensive merit, achieve enlightenment and liberate sentient beings from unimaginable sufferings and bring them to enlightenment quickly. So you are unbelievably fortunate to attend this retreat! Even if you can't attend the whole complete retreat, you can participate for two months, one month or at least a few weeks. You could even do just one week.
Hopefully this same retreat will also be established in Mongolia. Especially there, since the main food is meat, there has been so much killing and this practice helps very much for that. After the temple in Mongolia is built, hopefully thousands of people will attend the retreat there. Gradually too, I would like for this retreat to be established in other parts of the West. This retreat also blesses the country and brings so much peace, happiness and prosperity. Even if you know the teachings on how to meditate on bodhicitta, you still need to receive the special blessings of the deity, Compassion Buddha, therefore you need to do meditation and recitation to pursue the deity's blessing. Therefore the recitation of this mantra is one way to actualize bodhicitta, to be able to transform the mind into bodhicitta, and to make your meditation on bodhicitta effective.
Generally, according to my experience, in my home Solo-Khumbu in the Himalayas in Nepal, there are people who live their life chanting Om Mani Padme Hum and have no idea of the three principles of the path, not even the words. They can't read or even know the alphabet, but have great devotion to compassion and bodhicitta and live their lives reciting Om Mani Padme Hum. Such people are warm-hearted, very kind, very compassionate. This is a proof from my experience that it has effect of transforming the mind into a good heart and compassion.
           Without bodhicitta, you cannot cause all the happiness for all sentient beings. You cannot do perfect work for all sentient beings. That cannot happen, and you cannot achieve the complete qualities of the realizations and cessation, even for yourself. So you are most welcome to join a 100-Million-Mantra Om Mani Padme Hum Retreat!