Since receiving the update, I have done my best to cause a reboot or freeze-up. So far I haven't been able to do it.
While watching I have constantly, played with the PVR options, scrolled through all the menu items, added new recording events, changed the priority of upcoming events, deleted events, in short do anything I can to overload the memory of the unit. None of these things has caused a problem.
There are tweaks and enhancements that need to be done yet, which others have pointed out, but my 630 appears to be very stable with this update.