OK, first a bit of spoiler space. I was surprised at how quickly the film started, i.e. the lack of adverts/trailers. They had some still pictures for local restaurants while the lights were up, but they skipped the usual Dr Pepper adverts etc before the film. There were only two trailers - "Men in Black 2", and "Scooby Doo". To be honest, neither of the trailers looked particularly inspiring, but I'm sure I'll see both of those films when they come out, so I guess they had the desired effect :)
Onto the film itself. As I said, I really liked it. It was a new story, while staying true to the spirit of the comics in terms of characterisation etc. There were also a few classic scenes, in different contexts, and some references that only fans of the comics would pick up on (e.g. Peter's boss was Dr Connors, who becomes the Lizard).
I thought the casting was very well done in general. The only one I wasn't so keen on was Robbie Robertson (the black guy at the Bugle office), but since he barely even spoke in the film that's not a major problem. I recognised Betty Brant immediately (secretary) - I don't think she was named in the film, but she was in the credits. Speaking of the credits, they mentioned Lucy Lawless (aka Xena) as "punk woman", which I must have blinked and missed in the film itself :)
There are a couple of differences from the comics in terms of Peter's origin and powers. I'm quite happy with organic webbing - it was good enough for Spider-Man 2099 after all! Actually, the genetically engineered spiders and midget hairs also reminded me of Spidey 2099 too - it's basically a case of updating the story with more modern science. I hadn't actually realised that it was different species of spider with the different abilities, so that was educational. I also didn't realise until just now that they'd completely removed the radioactivity from the origin - I can understand why, and the fact that I didn't notice at the time is an indication that they handled it well, so I'll let that one ride.
On the realism note, I did like Peter's first costume - it looked like the type of thing you'd come up with in your bedroom. Trust me, making a "real" one isn't as easy as it looks (another story I'll have to post sometime)... I also liked the tweaks to the Green Goblin - it made sense for him to be developing that technology with military funding, rather than just coming up with it on his day off. In fact, it made Osborn a bit more sympathetic as a character. It reminded me of Quantum Leap a bit (Sam Beckett is pressured to prove his theories or lose funding), although that may just be because I'm in the middle of re-reading the "Quantum Leap: Prelude" novel at the moment. The change to his mask was interesting. In the comics, most artists take liberties, so it looks like full-face masks are actually real faces, that can show expressions etc. When you have a rigid mask that always has the same expression ("V for Vendetta" being the prime example), it's pretty creepy. I think this mask had a good compromise - it looked fixed, but then you could see part of his face through it. The gauze or whatever it was across the mouth made sense too, to avoid him being unable to breathe when flying at speed!
The changes to the burglar story also made sense. This gave him a good, human, reason to let the burglar go, and also reduced the coincidence factor of having the same guy show up at his house later.
I definitely liked the fight scene with the spinning thingies. This is actually a case where the film worked better than the comics. In the comics, you often see Spidey being aware of bullets, and dodging out of the way. However, the film showed that even when you have good enough reflexes to see the individual projectiles in slow motion, you still have to be sufficiently agile to actually dodge out of the way! That impressed me.
There were a couple of moments early on when I found myself cringing - a couple of the things that happened to Peter also happened to me when I was at school. That's not a criticism - I really identified with the character. There was one other moment when I couldn't help saying "Ye gods!" out loud, but I forget which moment that was...
As for the music, I though the main song was quite good, but the rest of it was just okay. It didn't detract from the film, but I wouldn't buy the soundtrack either.
The product placement was pretty blatant when it happened, but there wasn't too much of it. I was more amused by the cases where people clearly hadn't paid to plug their product - "Pet Needles" anyone?
I only really had two quibbles with the film:
a) I didn't like how Peter treated his aunt and uncle after he got his powers. That's more "Smallville" (the series) than Spidey.
b) Lack of realism in his fight with the robber. When I was younger, I punched my hand through a window, and cut the back of my hand in several places. (Admittedly, the sight of me standing there with my fist dripping blood worked to my advantage, but that's an anecdote for another time.) In the film, Peter smashed the robber's face through two panes of glass, with no apparent injury. I'd expect lots of lacerations after that, although none of them would be particularly serious. And yes, I realise that a certain suspension of disbelief is necessary here, but I prefer to reserve that for the core aspects (e.g. spider-powers).
I'm not sure whether I'll go to see it again with ICSF next week. I'd like to see it again at some point, but maybe not quite so soon. I'll think about that. In the meantime, I have the novelisation (by Peter David) that's been burning a hole in my bookcase for the last two months :) Mind you, I've just read a comment that says "Stay till the end of the credits for musical reward.", so that may tip the scales...