Latecomer review of
GURPS Mars Attacks on my blog:
http://blindmapmaker.wordpress.com/2...-mars-attacks/
Only got my copy last month here in Germany.
Short version:
A very good setting book - something GURPS desperately needs. It's not quite on the same ready-to-play level as Dungeon Fantasy, but it comes close. Don't make the mistake of thinking this is
GURPS Alien Invasions or something else. It deals with one specific setting and most of the crunch and GM advice is there in support of that setting and its style of play. Quite a few bits are useful for other campaigns, though.