I've just got one, taking over from my Vision M and I love it.
It's very slightly higher and wider, but about 50% of the width of the VM, but this allows a decent sized video screen. It also looks very good on the eye.
I use the Zune software and find it very easy to use and the software on the player is well thought out and easy to use with the navigation pad.
I do have to encode any avi's to wmv or mp4, but this only takes a few minutes each, no big deal really.
The album art works very well, leaving you with the album cover on the screen whilst the album is in play.
The screen is good, although not quite up to the VM standard, but the size increase more than makes up for this and the only real letdown is very slight blocking every now and then.
I find the sound quality very good as well, although the omission of a graphic equaliser is a bit odd in my opinion, but I'm happy enough. I'm using my E500PTH's with it, so I haven't tried the stock in ear canal earphones, but the word is they're a big improvement over the bog standard earphones that comes with ipod's etc.
No mains charger, the inability to drag and drop within Windows Explorer, no case, no graphic equaliser, limited avi support (easily sorted as I stated earlier) are the downsides, but nothing major enough to detract from the positives.