I, personally, do not find it to have the value that should go with that price.
I had a VERY hard time leaving the cabana, because we had paid for it, but I really didn't like the cabana all that much. the inside of it (especially as I was changing from my 5K clothes into a swimsuit) was hot and muggy. The outside...the loungers had cloth-covered cushions, which just gross me out to think about all the sweat and whatever else might be on those cushions.
My son liked the hammock, but spent about 10 minutes in it.
Husband and son used the mats and I think snorkeled but for some reason I just couldn't deal with leaving the cabana. The mats and snorkeling are such a small price compared to the cost of the cabana that I couldn't wrap my head around using them. DS couldn't ride a bike well at that point (but was too big to have training wheels) so we didn't use that.
Because of that, I couldn't like it. $200 less and it would have been fine for me.
But...Castaway is my 2nd fave private island out there (should I ever be invited by Richard Branson to his island I'm sure it would be bumped to 3rd), even when just finding some loungers and maybe an umbrella. I don't need a hammock (my skin marks up way too much for the rope hammocks!). Get off the ship, do the not-quite-a-5K, run back to clean up and grab breakfast and meet DS and DH (who slept in so they are more cheerful), head to the island, get in the water a little bit, put on my 30spf, and lounge all day. DH is generally kind enough to bring us lunch. Ah, nice day.
I don't need a cabana there. If I had liked it more I would say it's gilding the lily, but having the cabana just added stress (must enjoy it 100% of the time and have ALL the fun!!!!) for me so it was almost a negative for me.
(DH and DS do not have the same issues and will be sorely disappointed should we cruise
DCL again, because their personal in-house TA won't be trying for a cabana)