Now that I've gotten the nerd science nitpick out of the way, yay for Michael Keaton and the relatively low stakes of the villain plot. I loved that Toomes' big scheme wasn't the destruction of New York or killing everyone in the UN or whatever. Toomes just wanted to steal stuff and make money. He even tried to stay out of the limelight. It was also refreshing to see the bad guy so quickly pick up on clues to ascertain the identity of Spider-Man, which gave us the nice menacing scene in the car.
That said, I wasn't a fan of how lame the security was at Damage Control and on Stark's cargo plane. No cameras or guards in the Damage Control warehouse? Why did they have the lights on then? And Stark's plane was ridiculous. A completely automated plane carrying a priceless cargo of superhero tech that apparently had no safeguards against anyone hijacking it? Maybe Happy needs to find another job.
Finally, why play so coy with Zendaya? If you look in this thread, the news outlets were calling her Mary Jane back when she was first announced in the cast. She's prominently featured in the posters (moreso than any other female in the cast) so why rename her and act like her being "MJ" is a big twist? I don't get it.
Oh, and who was the guy at the end in jail with the scarred face?