Yes, I've seen it. Some notes (and possible spoilers) follow...
My review is now available online. Here are my earlier notes:
ARE YOU BETTER OFF NOT KNOWING PETER PARKER? "S-M 3" indicates the answer is yes. There's the ongoing trouble with Harry. There's the way the origins of Venom rest in his relationship with Parker/Spidey. Sandman, for that matter, is also entangled in Parker's past, and a deed that changed both their lives. (I am really trying not to overspoil here.)
For that matter, things don't go very well for Mary Jane in the new movie. I don't think this is a matter of Peter being poisonous, or even that he's Jessica Fletcher. I think the movie is going for something deeper here, not only a balancing of good and evil in the world, but an argument that the two are interconnected -- that a good act can have evil consequences, and vice versa. When you look at Sandman's arc, you'll see that even more clearly. Then again, I may just be seeing things because ...
THOMAS HADEN CHURCH IS SO GOOD. There's a closeup of him early on where his face says "tragic figure." And so he is. In fact, he's a far more compelling character than Peter. (And more so than Doc Ock in the second movie, even though there are lots of parallels between them.) So is Harry, for that matter, although "S-M 3" is so overstuffed that he gets shoved aside for a long stretch in the movie -- and that undercuts the payoff to his story.
HAVEN'T WE HAD ENOUGH OF MARY JANE IN JEOPARDY? Especially for the big finish. Third time around, after all, and that's way past too much.
IS THIS BASICALLY A POSTER IN SEARCH OF A MOVIE? Kind of. I mean, the black Spidey suit should launch a zillion screen savers and action figures. It sure had me ready to see this. But the movie doesn't measure up to the image. In fact, I suspect ...
THE MOVIE'S AMBITIONS HELPED BRING IT DOWN. With this thought to be the finale of a trilogy, it has a lot to do just tying up loose ends -- Peter/Harry, Peter/Mary Jane -- without adding so many other elements: the ugly side of the famous Spidey, as well as the battles with Sandman and Venom. The basic character pieces, along with Peter getting arrogant, could have sustained a good movie -- and the Harry/Peter conflict would have offered an excuse for decent action sequences. As it is, the closing scenes are emotionally effective; we just take a long, often slow ride to get to them.
SOME IDEAS JUST DON'T WORK. The big action scenes at night often look murky, and some of these felt as if we've seen them too often. On the other hand, the action with Sandman, especially in daytime, is pretty cool.
SOME IDEAS JUST SHOULDN'T BE TRIED. In this case, it's a dance sequence. You'll know what I mean when you see the movie.
And I know you'll probably see it. This is a review-proof movie, at least for the first weekend. I know I wouldn't be paying attention to reviews, including my own. I'd just want to see the black costume.