I was a TopUpTV customer for a while, but left the service when they switched over to the AnyTime service. Which they only did because they sold half their channel allocation to Channel 5.
The programs they selected for download seemed to be erratic and I really didn't like most of the stuff they advertised in their schedule.
Also, I got the TopUpTV branded PVR for my father-in-law when his existing Freeview box gave up the ghost. I can't tell you how bad it was, always hanging up, randomly not recording programs. We changed it out for another and this was exactly the same, so got a refund and purchased another model.
I personally would avoid it like the plague. Your better off with BT Vision, if you have, or don't mind having, BT Broadband.