I thought the humour was pretty bad in its execution. The humour shouldn't come from Dr. Kafka being a stupid, German mad scientist with lipstick. The humour should be nuanced and intelligent.
There were many instances when the writing felt lazy, trying to take easy routes such as [blackout]the defeat of Electro. Why did Spider-Man all of a sudden endure that much electricity?[/blackout] to mention one example (there were so many instances that I don't even remember them all, the whole film felt incredibly dumbed down). Overall I want much more thought put into the script.
Characters need not to be stereotypical archetypes or horribly over the top. That kind of humour is simply childish and takes you out of the film completely, leaving you embarrassed. I want a villain that is well written thoughout, simple as that.
While it was good to have continuation from the promise in TASM, the constant back and forth between Peter and Gwen, while realistic, was annoying to Watch IMO.
Have writers who know how to write things that are according to characters. Don't have Peter Parker learn about batteries via a stupid Youtube video for example. Don't sacrifice character for childish Comedy (see also: Max Dillon).
Think less is more. Don't try to cram in as much as possible just because the MCU is successful. Write the story and the plots for one film specifically this time, instead of having too much of a "to be continued..." mentality. No need to throw in characters like Felicia if she's barely even there. I want to see a film that has more in common with Iron Man 1 instead of Iron Man 2.