I've got Win 7 already. Not VERY different than Vista, but yes, its different. Here's how my experience went.
I downloaded the image, burnt the DVD and straight slid it in. I had some 25 gigs unpartitioned space on my HDD so decided to install it there. That would have left me with 3 os's, XP, Vista and Win7. Ran the Win7 setup in XP, chose the advanced option, chose the drive, and boom, its on. The interface of the installation WAS DITTO same as of Vista. I used a timer to time the install, it took exactly 23 minutes (Yes, 23 minutes, isn't a typo, I was surprised myselves). The boot loader was sorted very sweetly, with three options at the start now. The loading screen (The black one which comes on the initial loading) is now much more dynamic, the 4 MS colours keep shining / rotating in a pleasant way while it loads.
Right in terms of performance. Yeah its been all snap for me since the install (1 day). Fast, starts up like magic and shuts down too. However I had the same experience with Vista initially so I'm going to reserve my opinion here till I am able to install something concrete and then test it.
Hardware support, well I installed the Vista 32bit drivers for my nVidia 9600GT and they work uber cool. Never really was required to install any other drivers, everything else worked off the go.
The control panel has changed, UAC's probably either gone now or is disabled by default. The Windows Experience Index however gave me the most surprises. The rating system has changed, its now on a scale of 1 to 7.9 and has some new tests in it. Found the names interesting, dunno what they actually do.
But the best part is, all this in a BETA! Its stable, its fast, it works, and its a BETA, free till August 1. Couldn't get anything better, especially from a company like MS.
I'll try and get the screenies up by tomorrow if someone else doesn't.

Yeah I'm too lazy sorry, but apart from the taskbar or whatever you call the lower bar, not much is different in terms of interface.