I have a 16GB Zune HD and must say it's one of my favorite gadgets. It's easy and fun to use, the Zune software is exponentially better than iTunes and WiMP (Windows Media Player), and it's rugged. Yes, I've already dropped mine on the driveway. It suffered a few scuffs at the corners but that's all (solid state is wonderful!). I also often carry it in my pocket with no sort of case or other protection and there is nary a scratch on it.
My biggest hope would be that existing accessories are compatible. I have a car kit and a home AV pack for my 4GB. I know I'd have to get a different AV pack to do HDMI but I'd hate to be forced to buy new just because of a new connector.
And I gotta agree about Bluetooth. I already have the headphones that I use with my WinMo phone. I 120GB Zune (HD or not) with iPod touch-like capabilities PLUS A2DP? And Zune Pass? Now THAT'S an iPod killer.