Sloane was fantastic. His interactions with Bashir always made for great television. I wish that A) he'd been featured in more episodes, and B) that his death hadn't been so lame. Someone that cool should've had a way better demise.
I really never liked the concept of Section 31, so really 3 episodes was enough for me. I will agree that the whole "brain death" thing was lame as all heck though.