The rest of the park is a step below the Orlando water parks in my opinion!
I'll add my two cents to this thought.
As a stand-alone water park, Atlantis would be a minor one with fun but forgettable attractions. There's no groundbreaking one of a kind slides at Atlantis (except maybe the river/conveyor belt system that allows you to stay in the water/your tube indefinitely). Nothing is the tallest, fastest or loopiest.
But I think Atlantis is much like Disney in that it is not the individual statistics, but the whole package put together. Disney rides are not the most technologically advanced, fastest, or the best at any one thing. But they are the best when the story, ride, and total atmosphere are put together.
Atlantis is like this in that the water park would be ordinary if it were a concrete water park a land locked town, but its sitting on the bluest ocean in a beautiful tropical climate as part of a world-class resort. You can watch the ocean liner cruise along the Caribbean while you ride a conveyor belt up to a water slide....then when you get down, you can run from a pool to an ocean in about 50 yards.
So yes, Atlantis is not the greatest water park, but it is a pretty unique world-class attraction.