Personally, I'm thinking about getting one. Even if you prefer PC gaming, you have to admit that for $400, the Xbox360 gets a lot of bang for the buck. As for myself, I prefer PC gaming. However, I have no money and to build a decent computer that would produce a playing experiece nearly on-par with a Xbox360, I would have to spend around $750 minimum. I just don't have the sort of cash, and probably won't for a while, so Xbox360 is a good choice for me at $400 or $300 if I can live without the removable HDD.
What about the features and performance? I found both of those to be impressive on the Xbox360. I liked the wireless controllers, the design and especially the fact that you could turn it on and off through the controller. The performance was great, although less impressive than I thought it would be. Bottom line: if you don't own an HDTV that supports 720p or 1080i, then the playing experience will not be as great.
The thing that really irked me about the Xbox360 was the 2 different systems. I was really pissed that even though I only wanted the removable HDD, I would have to spend an extra $100 from the Base system just to get it. I didn't want or need all of the other features that came with the Premium system, I just wanted that damned removable hard drive.
All-in-all, the Xbox360 is a great system. I own an HDTV and since $400 is a hell of a lot cheaper than $750 for a new PC, I would definitely get it.