Summary
A good, solid game I find inferior to the original Quake.
The Good
Well, when combined with a 3D accelerator the 3D engine is (or at least used to be) mind-boggling, but the software engine is as bad as they get.
The background music is OK - nothing more - and the multiplayer play is really awesome (if your connection is, unlike mine, fast enough).
The Bad
Really low quality sound effects, terrible software engine and a terrible 1-player experience.
I find this game inferior to Quake, mostly because Quake would run on an unaccelerated 486 reasonably (not to mention a Pentium-class machine with a 3D accelerator - it rocks!). The original is also an awesome 1-player experience where as this game is completely no-fun in single-player games.
The Bottom Line
A good game, loved by most, revered by many. Get it and play it, then go back to Quake.