I just completed a stay there over the weekend as a diamond member.
The Good:
-Was given an upgrade to a junior suite, which had a gorgeous view of the ocean and bay
-Access provided to Regency Club
-Close to Sea World
-Shower pressure was great
-Courteous staff
The Bad:
-Noisy property (coming from airplanes and frequent weddings which are miked very loudly)
-Nothing besides Sea World, including restaurants, are nearby
-Dated feel; it's sort of like stepping back to the 70s
Overall, I'd say that if you just want to relax, the Islandia is a good place to stay because of the spectacular view. It's certainly not as bad as others have described. If you want to be closer to activities, though, you might want to stay closer to downtown.