We just got off of a 4 night Wish cruise and the total cost of the length of cruise Rainforest Pass was $224.20 per person. That includes an 18% gratuity charge.
This was our 2nd cruise on the Wish. They first cruise, the Rainforest was packed and hard to find loungers/heated loungers, etc. Our recent cruise, it was less busy and we always found a space to relax. So I think it's hard to tell how crowded it will be depending on the makeup of any given cruise. Same goes for relaxation level. Our first cruise, since it was filled and busy, people were very chatty. It was not a quiet spa like vibe. Second time, however it was as quiet as can be and very zen. Both were enjoyable but different.
As far as ammenities, it is indeed expensive. I look at it as quality over quantity. If I can spend a few hours at least twice and thoroughly relax and enjoy my time, then it's worth it to me. It really is beautiful.