I watched this movie at the theater when it came out, but I've probably only seen it once or twice since then. My 12 year old has been bugging me to see it. Trustin Common Sense, I decided to let her watch it. She has seen all the Heroes (NBC) episodes, so know up front that she's accustom to a certain level of violence and language.
I have to agree with Common Sense's review. It's appropriate for kids 11 and older depending on the child and the parent's leniency for violence or language. I listened for the "S" word and never heard it. Lots of "A" (rear-end) references, even by Peter's Uncle Ben. I don't remember Peter himself ever using bad language. There is a degree of violence throughout. The last fight sense was rather painful for my daughter to watch (as Spidy gets the snot beat out of him). There's quite a bit of blood to boot. So just be careful.
In the end, the movie was still an appropriate watch for my 12 year old. It has some good overall themes about what it means to be a hero that I enjoyed recapping later with my child. For the faint of heart, preview (as always) this movie before letting the kids watch, but I give it a thumbs up for 12 and over.