Got my G2 today and hooked it up after work, I'll try to give feedback as I play with it more but thought I'd give my first impressions when their fresh in my mind. Fyi, I've only tried the WDTV Live Hub before this so the only reference I have.
Physically it's not a bad looking unit, the feet are not level on the bottom of mine. Maybe by a 1/32" off on one foot so it rocks slightly. The remote doesn't have the feel of the best quality. I have a Harmony 880 so that's not a deal breaker for me and would go in the cabinet with the rest of my remotes after I program the Harmony.
I installed my 3TB WD Green hard drive, I have it wired with ethernet and running HDMI to my Onkyo TXSR706 receiver which feeds to my Samsung DLP TV.
I'm not sure what FU HO means but that's what I was greeted with powering on, if I was a woman I might be offended.

The first thing I noticed is the poor remote, I had to point it directly at the unit to get it to respond. Hopefully this responds better with the Harmony and isn't related to the receiver in the unit itself. The response was mixed even when directly pointed at the unit. In the main menu it seems that pressing the up or down arrow will cause it to move up or down sometimes one icon or sometimes multiple icons which got really annoying. The icons highlight blue when your on them and then at some point some start to highlight brighter white instead which is odd in my opinion. Going left to right also had similar issues for jumping or response delay.
Setup was easy, one thing I noticed was TrueHD was misspelled TureHD in the Audio settings. Setup was done in less than 5 minutes including formatting the drive. Again the remote response time or response time as it may be was a little irritating at times as there was a couple second delay from press to movement. I transferred my first BD ISO movie via USB that contained TrueHD audio that the WDTV just could not handle. Play back was FLAWLESS which was very encouraging. Putting the movie on or off pause was another story, sometimes it would and sometimes I had to repeatedly press the button to get it to work. The other button that seems to have little or no effect is the power button on the remote.
Anyway that's my first impressions and I'll post back as I play with it more this weekend and particularly after I program the Harmony to see if some of this goes away because of a lackluster remote. If not then I'm sure I'll be sending it back because if it's a little annoying now it will become a lot annoying in the future.