My partner and I did this on the Wish on our cruise in October.
It started with a foot scrub for both of us, we were chatting with the two ladies in the Spa the whole time, and they were both lovely. After this, they left us to use the Hot Tub for 20(?) minutes (can't quite remember how long). They left the room and it was just us in the room on our own, they knocked on the door and gave us 5 minutes notice for the massage.
We lay on the beds for the massage, face down, and had to remove our swimwear to not get the beds wet, but they respected our modesty really well. We had a choice of massage, I had a deeper tissue massage as per their suggestion (I have a sore back) and my boyfriend had a Swedish as it was his first massage. The massage was relaxing, with no talking during this section other than asking if we were okay at intervals. It was full body, so we flipped halfway through.
The beds did move at points, particularly when we were on our backs. I can't remember much of how the beds moved, other than feeling extremely relaxed and genuinely I forgot that I was laying on a bed, I couldn't feel it beneath me I was that relaxed. The massage was 50 minutes, and we were offered a longer one at the start (for a higher price).
After the massage, our hands were joined and a gong was sounded. The two Spa staff left, and we were able to put on some complementary robes and sit back on the little sofa where we had the foot scrub. We got some fruit and tea - there was a good selection of different teas, mostly herbal, but being British we requested English Breakfast and they went and got us some. The fruit was mostly tropical (melon, dragonfruit, strawberry, pineapple, apple, grapes, plus some more I probably forgot) and we were left to share the fruit and have our tea for the rest of the session. At the end of the session (which all in all I believe was around the two hour mark?) we got changed back into our swimwear (in hindsight we should've taken some spare clothes!) and we went out.
We were offered use of the Rainforest Room afterwards, but we had the Rainforest pass so it may have been because of this, but we elected to go back to the stateroom to get ready for the show.
All in all it was a really nice experience, and I would say worth the money we paid. I wouldn't do it every time, but it was a great way of relaxing and really unwinding and certainly worth it if you want to treat yourselves. It's aimed at couples for sure, and I'm not sure I would want to do the experience with anyone other than my partner.