System Shock 2 can be enjoyed without playing the first, the only thing your missing is some the back story concerning SHODAN and Citadel. But its 2 different plot lines if I remember correctly so anyone can have fun on System shock 2
Theres a group of guys on ModDB who made an upgrade mod to SystemShock 2 thats worth checking out.
EDIT: heres the link
http://mods.moddb.com/3329/system-sh...igh-poly-pack/