This movie was the type of science fiction that was more fiction than science. There were problems with the science that the movie-makers seemed to just gloss over (probably thinking, "Hey, it's just a movie. Who cares if it makes sense?" that really bothered me. Setting aside Khan's "magic blood" for a moment, there were also issues of how long it takes to travel from Kronos to Earth. Is it 20 minutes, like they say at the beginning, or the 30 seconds it demonstrates near the end? Were they stopped from reaching their destination or not when the bigger ship caught them? They were going to earth, and they arrived, but it indicates that they were somehow knocked off course, or, at the very least, interrupted.
Then, of course, there's the fact that Khan's blood has magical healing powers, and they can't explain it. That's wonderfully mystical and all, but isn't he supposed to be the product of 300-year-old science? He's supposed to be some kind of genetically enhanced superman, right? So why wouldn't they be able to explain why his blood does whatever it's doing?
These problems and others were why I couldn't suspend disbelief to adequately enjoy this movie.
This movie did a really good job of juggling a lot of information all at once. There were a lot of stars in this movie, and it would have been disappointing if it hadn't let them all shine. The character interactions were all believable and you're never going "Ok, now why is that guy working with this guy, exactly?" which is always a danger with this kind of mash-up movie. In general, the script really worked. My only complaint is that the villain's motivations are somewhat glazed over, but if you know the previous movies and comics you already know that information. That's really my only con, since you're supposed to know information going in.
Hulk is handled better in this movie than in any previous incarnation, and it's an ensemble piece, which makes that even more impressive. Without giving away any spoilers, there is one scene involving the Hulk that is worth the price of admission by itself.
This movie is now one of my favorite comic book movies. I enjoyed it about as much as X-Men 2. The characters drive the story, which I expected when I saw Joss Whedon would direct.
In conclusion, the movie was very good, is absolutely worth going to see in the theatre, but not multiple viewings (unless you absolutely have to catch every one of Tony Stark's jokes: some of them are pretty rapid-fire). If I was 10 years old again, I'd have rated this movie 5 stars: it's a lot of fun.
I enjoyed this movie, but it wasn't as good as the first or third installments of the Indiana Jones series. It made me want to watch another action/adventure movie, so it wasn't horrible like I was worried it would be, but it wasn't amazing, either.