Waltorious: I also advise playing System Shock 1 first. It's also worth taking a look at System Shock Portable, a freely-available version of the original game that mods in mouselook controls and high resolutions. The mouselook will help a lot, because the original game has a really strange control scheme that takes a lot of getting used to.
Link:
http://www.systemshock.org/index.php?topic=211.0 Enjoy! I actually liked System Shock 1 a tiny bit more than System Shock 2.
I actually download SSP yesterday and played it a bit, and it was better than I expected! With mouse look it's not too clunky, and the interface is pretty handy, actually. It has a different feel than SS2, more UU-ish (which makes sense).
Gazoinks: I'd argue that neither of those are true. SS2 recaps SS1 at the beginning, and even without that it pretty much stands on its own. SS1 is definitely harder to get into, but the two games are different enough that it seems worth playing even after 2.
BananaJane: You're still missing out because the 2nd game spoils a lot of the first game
Yeah, I wasn't saying that you wouldn't miss out, just that SS2 does make sense for the most part on its own, and SS1 is different enough to still be pretty fun (though clunkier, ofc).