I shall attempt to very briefly summarize/highlight the esteemed points of Arjaan Mun's amazing life and his greatness.
1) Though Arjaan Mun must have possessed many amazing psychic powers to a very high level, he never stressed those in his teachings.
2) He adhered strictly to the Buddhist percepts. He lived with minimal material possessions. Apart from his robes of discarded cloth and his alms bowl, he owned nothing else. He lived the life of a ascetic that is hardly found today.
3) He had the ability to communicate with invisible beings from many realms (from the lower to the higher realms). He was even able to teach the Dharmma (teachings of the Buddha) to devas (celestial or heavenly beings).
4) He went against the Orthodoxy/Convention of his time. While many Thai Buddhist monks were required to live in monasteries at that time as this was regarded as a wise political move by the Thai Royal Family to mobilize the Sangha (Buddhist clergy) to counter the political ambitions of Western powers (who were using Christianity to attempt to convert the Thais and hence gain political power over them), Arjaan Mun was one of the early pioneers of TuDong/ the Forest Tradition. Arjaan Mun went into the forests to seclude himself from worldly affairs and seek the Truth of the Dharmma (teachings of the Buddha).
5) Arjaan Mun relied a great deal on himself to reach Englightenment. Although in the beginning he had Arjaan Sao as a teacher, Arjaan Mun's later experiences were such that they were not within the scope of Arjaan Sao's (Arjaan Sao is another great Thai guru monk and the earliest or one of the earliest pioneers of the Thai Buddhist Forest Tradition) experience. Through Arjaan Mun's determination, ingenuity, resourcefulness and mindfulness, he was able to overcome the obstacles he faced and gained Enlightenment in one lifetime.
(Note to the reader: It is not possible for me to cover every single detail of Arjaan Mun's amazing life. For that, I would ask the reader to read Arjaan Mun's official biography, which can be found in AccessToInsight website: