i persoanlly love the benko. the queenside attack is just phenomenal.
Why the Benko Gambit?
Uh... there is an anti-Benko... but guess what! The leading opening theoretician (I think) has helped to counter that anti.
From what I read, Fedorowicz is the leading master with the opening (or, perhaps better stated, the top player who uses it as his main opening). The Benko used to be my main defense to 1.d4, and I think I may go back to it at some point.
Lead in development, amazing possible attacks. a1 - h8 diagnol and ability to win the pawn back with PRESSURE.
Federowicz wrote an amazing book on it. I play the Benko.