So yeah, I broke down and got SC2. So far, the campaign's pretty freaking fun. Done about 5 missions or so. Pretty much you get one new unit per mission, but after the first couple you get to pick between a couple missions as to what order you do them in. Storyline's pretty good so far, and between missions you get some random stuff to do like picking/researching upgrades to use in missions, mercenaries for hire, and the like, not to mention interacting with the various characters (Don't think this is a spolier, your main guy is Jim Raynor again). THe between mission stuff kinda reminds me of a firefly set - half sci-fi, half western.
Some of the basic achievments require doing certain things in missions on hard, and the step up in difficulty is noticeable. Haven't tried insane difficulty yet.
Otherwise, the usual sense of humor is everywhere...medics say "Please state the nature of the medical emergency" - SCV's will say "AH! You scared me!" and the like.
(Although there are plenty of places in 40k that could be considered half scifi/western.)
