Yeah, I talked to some friends who didn't see it either. Seems to be on a theater by theater basis, for some reason. We were able to see both Spidey and TDKR with our showing of Avengers.
From what I understand, it isn't necessarily a straight "ultimate" version of the story, although it may have elements from both universes (and maybe some new stuff). I can't say I'd be any less excited if another Raimi/Maguire version was on the way, but I'm excited since it is a new Spidey movie nonetheless. What I've seen so far (particularly the recent trailer) has me pretty excited. I'm sure it isn't going to hang with Avengers/TDKR in terms of money or anything, but I'm still excited for Spidey to hit the big screen again.
Man, I really wish Marvel could get everything "under one roof" again though. It would be so great to see the cinematic universe crossing over even more with Spidey, Wolverine, Fantastic Four, the X-Men, Daredevil, etc. It is too bad they couldn't even just work out a cameo or something, but the studios are all too greedy for that it seems. Not that a movie like Avengers needed more going on, but it would be neat to see that type of "invading army" scenario where heroes are showing up from all over to help out.