The one in the original post is actually a very handy decent tool. Does actually do quite a few service lights too and does all the codes.
Reads the MK4 well, engine, immobilizer, door lock faults, radio etc.
I bought one in an emergency once as didn't have VAG-COM to hand and it does well.
Definitely worth the £34.95 with emergency shipping it cost me. If I just want to purely scan fault codes I'll grab that before getting VAGCOM out just for convenience.