I agree whole heartedly with Onizuka, and I was convinced I'd be selling it after a month or so!
I'm a hardened PC gamer, keyboard and mouse all of the way, and was beginning to put together a new high end gaming rig. But then I looked into the 360, saw what it was (on paper) capable of, and put a pre-order in for one as a cheaper alternative to the gaming rig.
I've only ever owned a console once, and then for only around 4 months - a PS1. Never got into it that much, thought all console games lacked the depth of their PC counterparts and sold it on. Plus I thought FPS on a console would suck.
But with the 360 I've been amazed. Not just because of what it it capable of (COD2 graphics are fantastic, and the gameplay is the same quality as the PC version) but because of my virtually instant conversion consoles. After a week of COD2 and PDZ I've nearly mastered the art of FPS on a console. Not as precise as a keyboard and mouse, but I'm getting there. Needless to say the gaming rig has been put on indefinate hiatus!
But the killer app is definately XBL. Its what online gaming should be - simple to access and play. With the demos and marketplace it really is fantastic. All I need to do now is to get it to work on my network! (I've got the wireless adapter coming).
Yes the fan is loud. Yes the DVD drive is loud. But during gameplay you wouldn't notice it at all. During DVD playback you would. Which is a shame, as I was wanting the xbox to be a decent replacement DVD player. But as I've decided to add a Mac Mini to my 26" Samsung, it will be taking care of DVD duties.
So I'd give it a 9/10...