My friend used his 7 night cert here and had very good things to say about the private island but was not too impressed with the actual hotel. Also said most of the guests there were a lot older which was a bit strange, he's in early 30s
The guests in the adults only tower were a little older, but there was a mix.
I'm in progress of writing my TR. I think it's a fine hotel. Room was clean, and new, albeit small. There was a chaise with a small table that was ideal for eating. Service was fine - we had to chase them down for a few things with them heating the meals but otherwise, no significant issues. Housekeeping did a good job, they had turndown service, free bottled water. Nothing much on the property that's so exciting to do, but since we spent most of our time on the private island, it didn't bother me.
I was in marina, can't speak to Island tower rooms. I think one would be hard pressed to find a better overall value for CC certs.
If I were paying points in the future and didn't care about using the cert, I might consider the cat 6 Marriott Solaris which is definitely more popular and nicer, though lacks the private island.