The concept of the world I liked. It was intricate, and well-thought-out. The way they meddled with genes and technology gave it a good variety, and also a great range to play with. Without spoiling the story, the Earth origin story was believable, and it gave a good explanation to what we saw.
The story itself was good. There were some humorous moments, like the bureaucracy. There wasn't much of a twist, the "mystery" element was quite obvious after the first about 30 minutes. The action was fast-paced, however, and looked great.
The romance aspect was very minor, and a bit forced. It was obviously coming, but it didn't seem to actually play a role in the events, or in how the characters interacted with each other. If they had just been friends, I don't think it would have made much of a difference. Note to film-makers, there doesn't have to be a romantic aspect in every story.
The casting was also good. Mila did a great job as Jupiter. She was as confused about everything as can be expected, but at the end could harden her face and kick some ass.
Channing is starting to be a bit overused as the resident muscled love interest. Not that he's not hot, or that he didn't growl appropriately, but I'm starting to feel bad for every other muscular male actor out there. I did feel, however, that his role was rather generic, and repetitive.
So the movie itself didn't blow me away in its complexity, just the pictures did. However, it is a fun sci-fi movie, and I would love to have a sequel, or even just books, because I want to know what happens to Jupiter in the future.