Viewed as a hotel, the stay can be described as interesting and pleasant. However, anyone expecting a deeper insight into esoteric or Shingon Buddhism will be disappointed. Of course the evening/morning rituals and the vegan food are interesting and even spectacular, but hardly anything is explained and there is no opportunity for conversation or other contact with the monks. Since the journey to/from Osaka takes at least 3.5 hours, you should definitely plan on spending 2 nights in Koyasan so that you can see the sights without rushing. My impression was that the stay primarily serves to finance the temples, and not to introduce visitors to the teachings of Shingon Buddhism or the monks' way of life. I wouldn't travel to such a remote area again for this little insight.
The room was located in a stunning and truly beautiful temple. The person who welcomed us was incredibly kind and, the next morning, gave us a full tour of the temple and its different areas. The room was a bit cold in January but amazing, and the public baths were not always very convenient, but the hot onsen at the end of the day, along with the friendliness and authentic atmosphere, made the experience truly wonderful.