Just saw this in the drive-in the other day. The movie wasn't bad, but it was just totally unnecessary. There really was no major innovation in the plot, it was just a cash grab. I'll stay away from real spoilers, but if you don't want to know anything at all about the film, don't read on.
Well, it wasn't a bad film, I just had a thought going on that in my mind that possibly they wanted to fix a bunch of things that could have been cooler from the first film. The mechanical webbing being one. Stupid thing is they added it but there was no point in doing so. He never ran out of webbing, never even needed to change a web cartridge. They were more innovative with his actual fighting though. He fought more like a spider, and used his web in a couple really clever ways.
They completely failed trying to capture the tragedy behind spider-man. It kinda devolved into a "ooh, spiderman is all cut up and comes home late". I always thought of Spidey as the one superhero you wouldn't want to be, because his life gets crapped on more and more every day. I think they tried to convey that, but it just didn't work.
Oh, and Emma Stone does not pass as a high schooler. At least a high schooler who isn't on meth.