Atlantis is on Paradise Island, not its own island as there are several other resorts, hotels, and other businesses there.
Youre right about the service being terrible. For the most part, the staff is not pleasant nor helpful. In the shops they are downright snooty. Both times weve stayed there, they try to make you feel special at checkin. Our first visit I had booked a oceanview room in the Beach Tower (cheapest). They told us upon checkin that the room wasnt available and that they would upgrade us to the next tower. We ended up looking over the roof of the lobby and the parking lot. I complained and we moved again back to the Beach Tower with an oceanview-a little sliver at least (looking over another roof littered with trash). Last year, same thing-our room wasnt available as we had booked, but we would be upgraded. This time however, we came out on top (well not quite-the $25,000 Bridge Suite wouldve been tops). The staff was a little better, but when you consider what youre paying, they fall way short.