Come on guys, of course Peter learned something in this film.
After he gets his powers he isn't necessarily abusing them (basketball scene is what I can think of), instead he kind of neglects his responsibility of being Peter by keeping Ben and May up all night and forgetting to pick May up from work. He then gets the speech from Ben about having a moral obligation to do good things for others if you can.
Then he witnesses a crime and lets the robber go. What I like about this scene is that it doesn't matter that he is Spider-Man, that any regular person in that instance could call the police or tell the clerk the moment it is happening. But Peter is upset and lets it happen. Then Ben is killed.
Then Peter goes out at night, creates the costume/shooters, to find the man who killed Ben. He is stopping criminals but not to help other people but really for justice against his uncles killer. THEN Captain Stacy gives Peter a reality check and tells him that what he is doing is not protecting innocent people for greater good but really doing all this for himself. Reminds me of what Ben says to him at school "so all of this is about getting even". That scene with Stacy is where, imo, Peter really understands what Ben meant with his speech.
Then that very night he goes to the bridge and stops the lizard, saves the kid, and calls himself Spider-Man. We then see him in his room, staring down at his mask. I've seen people say that small scene is about Peter, after just hearing the dad say "my son"..or something...thinking about his own parents absence. I see it also as him staring at the mask and understanding what he can be as Spider-Man.
Then, he even tells Gwen he has to go after the Lizard because it could have killed innocent people, and that maybe this is his job. He even has another conversation with Gwen in her room and tells her this is his responsibility and he has to stop it (Lizard). Sure, not going out after the carjacker can be seen as bad writing to people, but I also see it as Peter understanding that it isn't about getting even anymore and that he has a responsibility to protect others.
In regards to the ending, I mean I think everyone here knows Peter and Gwen will end up together or obviously still want to be together. The "those are the best kind" line to me seems more like foreshadowing to the events leading to Gwens death. But I don't think just cause he basically implies that he still wants to be with her means he didn't learn anything in the film. Who knows, maybe she will be dating Harry for the majority of the next film