I actually found Mighty under Bendis to be horrible, but it got a lot better when Slott came in with his own cast of Avengers. The writing was better... unfortunately it was also largely ignored by Bendis in the rest of the Avengers line.
As far as Bendis goes, I kinda think that his Mighty run was the worst of his stuff. The ideas were fine but the female Ultron, the horrible execusion of thought bubbles, and cho's art (which I'm not a fan of) all brought it down for me. His second arc on the book though with Bagely was pretty good.