The story is extremely thin, even for a superhero movie. What annoyed me in Age of Ultron was how it just glossed over so many things. But good moments don't make a good movie.
The romance between Hulk and Black Widow was interesting, this universe has been weirdly sexless so it was nice to see some tension between the characters. There are good, fun moments spread all through the movie, don't get me wrong I liked plenty of stuff in it. Especially the ending which feels like it follows the first movie beat by beat. Age of Ultron is pretty much the same movie as the first one. If you wanted something different, some change to the Marvel formula, you'll be disappointed. I'll say this: If you don't mind more of the same you'll probably love this movie.