Ult Spider-Man is not only the best Ult title right now, it's leaps and bounds better than the others. No one thought a new Spidey was a good idea, but Bendis managed to write the character and plot in a way so as not only to keep you interested, but you can't help but root for Miles. I do miss Peter, but honestly probably like Miles more. Also enjoy that Peter's supporting cast play an important role in the book, and will undoubtedly help keep Miles pointed in the right direction. I'd also like to see Fury take more of a surrogate father role (like he did with Peter, but more distanced) as a way of fulfilling his intentions, if now impossible to do for Peter, through his replacement of Miles. In other words, I'd like to see Miles actually recruited to the Ultimates when he's old enough, and train regularly with them in the meantime. Think it'd be a great reason to bring Spider-Woman back to the book, as a sort of big sister character (albeit with similar powers, so the role works two-fold as both a trainer and emotional rock for the young Miles).
So again, while I miss Peter, I think the best thing Bendis did for the title was kill him off and take this new approach.
And yes, the twist on Uncle Ben's murder with Miles playing an indirect hand in Aaron's death was pretty smart.