Don't bother. Not worth the price of admission. For me, anyway. Maybe for someone who's not familiar with the source material. But for someone who's read the original Galactus trilogy it's pretty teeth gnashing. Awfulness abounds, particularly in regards to technobabble. Oh, and Jessica Alba, pretty to look at but can't act. They did manage to do right by Doom, though, for most of the picture which was a welcome change/correction from the first. But my main bone of contention is that I didn't think it was possible but they did Gah Lak Tus and they did it worse.
Which, I actually didn't mind Gah Lak Tus, it fit the Ultimate universe. I'm not opposed to altering, updating these stories if it results in something better. And the idea of some kind of a Von Neuman Berserker is an interesting, valid subject for a story. Very sci-fi. But, you know, not quite up to the standards of the original. The idea of Galactus was that he was a god. That he was beyond good and evil. And it was somehow up to the Fantastic Four to outfight or outthink a creature so far out of their weight class. It's the story of what happens when the ants want to keep you from stepping on their hive. What amounts to grey goo doesn't have nearly the same dramatic or emotional impact. And the film makers couldn't even capture the sense of weirdness, of ineffable alienness, of other that at least Ellis got right with his swarm of space locusts. Ending was pretty lame, too.