Not bad at all.  A bit worn down from the countess number of sci-fi action movies before it, but most of those sucked anyway.

Blantant Plot Device Theft:
1. Someone must utter the line "He's a Congressional Medal of Honor winner.  He know how to fight."
2. Protagonist thinks woman companion is weak; woman companion kicks much ass and he throws out a one-liner.
3. Bruce Willis
4. Don't Touch the Red Button

Plot Revelations About Life:
1. Aliens always hide important artifacts in their body cavities.
2. The "perfect being" is an airhead model with a weird name
3. Science?  This is Sci-Fi!  We don't need no steenkeeng science!

The Acting: 

Bruce doesn't live up to his 12 Monkeys performance.  He's been doing this so long, though, that it doesn't matter how different it is; it's John McClaine in space.

The rest of the cast is good, too, with Milla acting like a spaced-out chick in my writing class last year.

The Action: 

Classic runandgun, with some very fine Bruce pistol-play.  Some of the slapstick comedy is better, though, especially the scene where everybody (including the kitchen sink) try to recruit him.
 

The Directing: 

Very good, very fluid, looks incredibly cool.  He gets precisely what he needs out of the actors and lets them go with what he gives them.  Gary Oldman is a perfect example of it.  He is a seething hatepot, but is not overthetop (Tommy Lee Jones in Batman Forever, anyone?).