The 360 interface is perfect, in my opinion. And not to mention Microsoft will be doing major updates of it twice a year, so it will always be getting new updates and features.
That's the thing: They've
really improved it over time. I was by no means sold on the idea with the X-Box. It was all right but nothing close to what it is now. And coming into the 360 era, I wasn't remotely interested in their system or Live. After playing my friend's though, I'm pretty much sold on the whole thing -- so Sony's announcement of their pricing just made the decision to break from our original agreement all the easier.
[For those that don't know, the agreement my best friend and I had was this: We would both own a Wii, he would buy the 360, and I would get the PS3. Needless to say, that's been ammended slightly. Thanks, Phil and Boys!]