The VI"P612 is not only reliable, it may be more so than the 722 now. The built in OTA module works flawlessly, no problems some 722's have of freezing with the add on module.
Couple of tips to ensure reliability and longevity, applies to some other electronics aside from satellite receivers as well.
1. Not only keep in a well ventilated area, but use a small fan, like a woodstove room to room fan to keep cool. If you do keep it in a cabinet, if there isn't an opening in the back make one, and put the fan to draw the warm air out and try to have some kind of opening in the front, leave the door opened just a little.
2. Just like a computer, it needs to be reset from time to time. I keep mine on timers so each night, after the update takes place it resets. You can just unplug it every few days also.
I have not has one problem in a very long time other than the rare time the guide does not fully load during an update at night. That is not specific to the VIP612. I routinely have all three tuners recording, and sometimes while I am watching the DVR. No hiccups.
When the guide is correct, timers are not an issue, they seem to never misfire.