Well I also have the latest beta for my 721, and while I shouldn't say anything I have to say I'm less then impressed. There are still stacks of bugs. The reboot when 2 timers fire at the sametime - still exists. The Superdish Pointscreen barely works when you use DishPro hardware. When you exit from watching a PVR event don't change channels too fast or you still get a black screen. Don't change channels too fast using the remote, the unit will reboot. Don't lose the signal from the satellite as all kinds of random issues will occur - certainly don't expect the 721 will record even if it has the signal from another satellite.
Basically if you're a gentle user of your 721 you will find the coming upgrade works quite well. If you're a power user who tries to take advantage of the dual tuners and recording abilities you'll find they added some features, but didn't fix the critical bugs.
I'm seriously pained to have to say the above, but please people, don't get too excited - even after you've waited all these months there is no miracle cure for the issues the 721 has.