I just got back from it. It took me awhile to get into it but I ended up enjoying it. The first half was pretty slow for me before he became Spider-Man. But the second half picked up nicely.
Thought the web-slinging effects were awesome and that fights between Spidey and Lizard were great. I was glad they kept the robber origin intact though I felt it was odd that he didn't end up finding him. As pointed out, there seemed to be a lot of plot threads that never got resolved.
Although too old for the role, I thought Andrew Garfield did a great job. I liked the fact that Spider-Man actually told jokes when he was in costume. I never understood why Sam Raimi never bothered to make Peter funny when he was in costume. Emma Stone was really good as Gwen, much better than Kirsten Dunst as Mary Jane in the original trilogy. She has good chemistry with Garfield (considering they're dating in real life, that shouldn't come as a surprise) and it was refreshing that the entire final battle didn't consist of Peter having to rescue her.
The rest of the cast did a great job. Denis Leary is always entertaining and his dinner scene with Peter was fun. I had a feeling things were going to play out with him like they did, especially since it came from the comics. Martin Sheen manages to do likeable characters really, really well. Sally Field definitely looked like she had some scenes left on the cutting room floor but made the most out of all the scenes she was in. The actor who was really wasted was Irrfan Khan. I saw that guy on In Treatment and he's an amazing actor. He might as well have not been in the film. Although he really annoyed during an interview I read with him last year where he said he originally didn't want to be in a "violent American fantasy."
Ifans was very good as Conners and I liked the design of The Lizard. I take it there have been some storylines in the comics where the Lizard maintains Connors personality? His "make everyone a lizard" plan reminded me of Doc Ock's zero energy plan. That's the one thing with Spidey's rogues gallery. He has a lot of memorable villains to be sure but most of them are either in it for crime or to kill Spider-Man. He doesn't have many "rule/destroy the world" types to fight. So they give Spidey's villains in the movies scenarios where Peter has to save the city from destruction and so on.
Parts of this film definitely felt like a remake of the first film. Telling another origin story wasn't necessary and the film was better once Peter became Spider-Man. But I did end up enjoying it and I think the FX has gotten a lot better. I can't say I'm looking forward to the return of Norman Osborn though.