Been there, done that.
Well, we all know how big of an impact the original Counter-Strike left on PC gaming. Even with Counter-Strike: Source available, there's still a fair amount of people that play the original. So its really no surprise they decided to bring it to consoles, and of course the one closest to a PC, the Xbox.
The graphics are fine. There are really nothing special, but they're tolerable and get the job done. It's pretty much just a direct port of the original PC version, although i personally think it may even look a little better on the Xbox. It does have solid performance though, no frame-rate or pop-in issues.
The sound work is pretty basic. The only music really is for the title screen, and the only voice work is short sayings they put in just in case you don't own a mic. The explosions and gun effects all sound good, but once again, it's an old game so it's not exactly competitive with some more modern games in terms of sound quality.
The game-play is where Counter-Strike generates most of it's critical acclaim. it holds together surprisingly well on consoles. Obviously most people would rather be using a mouse and keyboard to play this game, but the Xbox controller works just fine. You can play on Xbox Live with your buddies to have a good amount of fun. If you don't have Live this game is pretty useless, although you can still waste time playing around with cpu controlled characters. Honestly though, this game is such a better experience on PC with mouse and keyboard and mods and such, you should really just go with that version, or better yet, go download Counter-Strike: Source off steam, it even runs on my old Dell Dimension.
This is a decent multi-player experience online for your Xbox, but you're better off playing Halo or Ghost Recon, or the PC version of this game. You can probably find this game for really cheap though, and generate a couple fun afternoons from it.