I have the Zune 80 GB and love it.
The only things that I wish were different is that there was "more". More options and additions to the interface. EQ (I wouldn't usually use it), some preset themes, able to delete from device, etc.
I was a Rio Karma owner, then Zen Vision M. Use of video is important to me, along with AQ.
The ability to actually hold the songs I want (for some reason I really want at least 30 GB with me...) and have plenty of video space is perfect. H264 hardware support is nice to have but I wish some additional containters were supported (only m4v)
Points are made about the pixel density. And they are of course very valid, and it would look better with higher. However, for me moving from a 2.5" diag to the 3.2" of the Zune, even at the same rez was a huge plus. Videos are far more enjoyable and at the typical distance I hold it while sitting it is a great compromise.
Also for those that want it, there is an awesome dock solution. Component video out, line out audio, etc. The ability to output full DVD rez, even with h264 over component is pretty cool (I do not have the dock, but could see this as being a really good feature for some)
The AQ is very good on this player, at least from a pick it up and casual listen standpoint. I haven't had the chance to really sit and listen but first listen with my Shure E4's and it seemed very open and clear. Compared to the ZVM, much better stereo seperation and less "in your head" sound...open and clear. Bass response at first listen seemed a bit stronger but the ZVM has EQ to more than offset if that floats your boat.
Overall very highly recommended from the hardware standpoint for someone who wants a device with good storage size (over 30GB), great screen size for videos, and a nice interface. Real button presses with touch is a very nice balance.
My biggest complaints: more fluff and features...stuff that can be added in a firmware update...but mostly the fact I need to use the Zune software. Looks fine, etc...but I hate having another program, esp with WMP11's built in functions...I mean come on MS!!!