If you want Quake 4 get it on the PC! (I got my copy of Q4 for free with purchase of my 7800GT.)
Q4 is a poorly done port from the PC, it suffered horrible framerate drops, I think someone said as low as 10fps which is not acceptable.
In general it was a good game, much better than Doom3 since you can work with team mates (AI) to take down enemies, get some time to drive vehicles, and even a nice surprise about 3/4 the way in. I cheated and beat it in god mode cause there is no way in hates I could beat it without god mode, especially the bosses. I did beat Prey another great game off the D3 engine.