The 360 is not "slim". But I said that in our first post about the new 'box - so what else is new? Well, as you can see clearly here, in a picture from Engadget, it is no all that much shorter either. I'd call an inch, maybe plus a half with the originals' HDD.
But guess what? Engadget are also reporting that it's about 1/2 an inch deeper than the original too - so there really will be little to no space saving going on.
Microsoft's claim to "whisper-quiet" has also been put to the test, when playing a game (and that is what it's for, right?) they've said it's no quieter than the original, with a very prominent low humming noise.
So in short, it's not smaller, it's not quieter, but it does look beast (in the good way) and for £199, why not if your looking for an Xbox. If you buy it, use it vertically though. It looks so much better side on than from the front like the shot above, I reckon. I can't believe the designers ever looked at that angle in the front plate, actually from the front.