The biggest turnoff we're seeing - even with the paid version - is the endless spam for 'nonsense' add-ons. Granted, you can disable most of that, but having that default to 'nag the hell out of me for useless tools to buy' is a very bad business decision IMO and makes the product feel cheap.
The UI in the latest AVG is gorgeous. Functionality so far seems very good, and it is adept at catching things. But the pushing other paid crap really should stop at the door once the primary product is purchased. For example with the PAID Internet Security version if you run the AV scanner it pushes you to the cleanup tab, then says 'Buy and install a crappy cleaner for another $44.95!'.. No... NO.. NOOOOOO.
Leave your PAID people alone with what they paid for.