FWIW, I am putting together the Adventure Island for my turning-5-this-weekend son tonight...and I bought it at TRU and got the free pool. We've already opened the pool, and it's a decent set - it has a working manual water pump that pulls water from the pool and operates a little overhead shower. It also has a full family of mom/dad/boy/girl which is nice. It won't foster a lot of imaginary play by itself, but it could make a nice setting for a pirate invasion.
Seems like it's overshadowed by the larger pool set with the water slide, though, which might be why they're giving it away.
Thanks for the info! I decided to order adventure island from B&M so I could get the pool and get the $10 gift card for spending over $75 (offer expire 11/17). I'm getting the pirate ship from ebay since it's not in stock at our store.