I have two HR20-700s. I posted a mini-review here after I had the first one for a couple days. It's still not 100%, but things have been getting much better. As far as UI and features go, almost everything about it is better than the DirecTiVo boxes.

The current software should be considered beta, but it generally behaves well. Sometimes a recording will get botched, but it happens way less frequently than a couple months ago. OTA ATSC (no QAM) was enabled right before christmas, but was available to anyone that wanted it a few weeks before then. The way the HR20 gets software updates is over the satellite dish. A couple times, DirecTV has put a new build on the satellite for a couple hours during the evening. Since the boxes only look for new software early in the morning, only people that knew to force an update within the specified window would get the new build. This is a great system to allow everyone to stay on the bleeding edge if they want. It's something that never happened with Tivo.

The HR20 also has a crude form of HMO working with the built-in ethernet port. So far music and photo streaming are enabled, but video streaming should be coming soon. DirecTV claims you need an Intel Viiv compliant PC, but I have it working on my Opteron running WMP 11.