I agree with Film Crit Hulk's take wholeheartedly, both in terms of its strengths and weaknesses, and especially about how it suffers from the "Marvel fatal flaw."
I think my biggest problem was the first hour was basically a repetition of the same idea: Peter want's to be on the Avengers, so he blows off his friends and chances to do anything at school, over and over and over and over and over again. Honestly, I felt at least half an hour could have been cut without any real loss.
As regards Keaton's line about "Native Americans," I believe the preferred term has actually gone back to being American Indians, because Native Americans more accurately refers to the Inuit, or that's what I was told by scholars studying music traditions of American Indians, so in addition to the line not making sense in context, it was dating itself as well.
The one scene that really stuck out to me as pointless and out of place was the gym scene where the three girls are playing Marry, F*ck, or Murder with members of the Avengers. I'm sure high-schoolers play that parlor game, but I'm equally sure that the high-schoolers who do don't censor the f-word when they play it, which of course had to be done to keep a PG-13 rating. And since that's the case, why script it in the first place?
And speaking of needless crudity, I'm sure every middle-schooler with the name Peter is really going to hate the film, or at least the party scene at Liz's.
On the plus side, Keaton is one of the best Marvel villains, the tie into Civil War was well done, and Holland is a very likeable Peter and Spiderman.