There are a lot of holes and flat out misrepresentations in that theory:
http://www.aquaticape.org/aatclaims.html
But juxtaposed to the alternative and accepted evolutionist theory that a primate living on the dry savannahs of Africa for no apparent reason grew a huge brain, lost its fur, started developing webs twixt its digits, and a layer of fat under its skin, this one has always seemed to me more logical and reasonable. But hey, it's just a theory.
If you're going at it from a creationist viewpoint then that's a different argument entirely. Personally, I have more respect for that idea than I do for what passes for accepted wisdom among afro-centric paleo-anthropologists. The latter simply refuse to debate or look at evidence which doesn't fit what they wrote in their last paper.