So, being the shallow person I am, I am going to go ahead and judge this book by its rack-mountable cover, its not gonna be cheap. It can record up to 100 hours of HD content, and since it is for the DirecTV network you can bet users will have plenty of HD content to record.
It will support 1080p output, through its pretty Optical HDMI port. There is a whole slew of ports pictured on the back, but none of them are OTA antenna connectors for recording HD over the air.
The price is as yet unknown, however the release date is rumored to be sometime in November. If you have a rack-mount entertainment system, and have been looking to replace your old DVR or get one to begin with, I think you now have something to look forward to, chances are that if you have a rack-mount home theater system, you know what this level of quality of a component usually goes for, so be prepared.
Directv hr21 pro hd dvr image leaked [via technabob]