Oldie but Goodie - If you missed it, check the demo.
I just downloaded the demo myself, just to see a little of it again for the nostalgia of playing a game I really enjoyed way back when.
The graphics are quake II era and that's about as far back as I'd want to go today myself but games of that time period and up all look pretty good I think compared to thier predecessors, even if nowhere near the quality of today's newest games. Anyway, the gameplay here is good and I'd recommend you play the demo just for fun if this interests you. It's a small download and if you really like it as I did you may just want to spring for it on ebay where I doubt you'd pay more than 10 bucks, shipping included, for a new sealed copy of it.
As for the multiplayer, somehow I doubt you'd have any luck finding people still playing this but if you did, that would be pretty good fun I'd say.