I have had a 722 since September 07 and have been very happy with it. Though I have read where some people have had problems with it. I used to have a cable Motorola 6416 box and it was much slower and didn't really compare to the speed and quality of the 722. I really like the storage space available on the 722 due to it having a 500Gb hard disk. I use the TV2 tuner for viewing tv on a computer (with a tv card) in another room and that works great. I had to extend the RF antenna for the receiver though in order to get the signal through a couple of walls. All in all I would recommend the 722 over the 622 (at least from what I have read about the 622).
FWIW. Just my 2 cents.