This 1000 times. I even read the book with his backstory. Just a total tool.
He should have been a squadmate option in ME2 in the same vein as Morinth. Only recruitable if you're playing Renegade and are willing to do something horrific to earn his "loyalty".
He still betrays you either way for the Illusive Man, but it would have been better then how they introduced him and presented him in 3.