I've only played the base set so far (Hoax vs. Vulca), But I'm really enjoying it. I'm rating it a 7 for now, but it could easily go up once I've tried out a few other races. UPDATE: I now have a couple more races (Mimix & Khind), and it's just as interesting as ever. UPDATE (Jul. '08): I'm upping this to an 8. I guess that means I should pick up the rest of the decks!
The ships are a neat addition. I need another play or two to decide how much I like it. UPDATE (Mar. '14): It's a bit swingy, depending on if you draw one of the ships early enough, but bringing down a "ship hammer" on your opponent is pretty satisfying.
I won this in a contest, but it's actually a pretty neat little game. The mechanics are unlike anything I've come across before. The card play is a bit opaque at first, but it's actually surprisingly thematic once you get into it. UPDATE (July '11): I've played it 4-player partnership, as I believe it was designed to be played, and it definitely was my best experience of the game so far. If you're on the fence about this one, try it this way!