I've bought a few bits, and the experience has generally been good.
TimDrayton; bought a frame off him; it came with extra bits I din't even think were included in the price! Superb service, and seems like a top bloke.
Coolhandluke11 gave me a mobile 'phone for nowt, after mine got stolen from me. Very kind. I stuck a few quid into a guide dogs charity box for that one.
Firestarter; bought a shock pump off him. Even though he's a Bulb-End, he seems like a top bloke too!
There have been a few others, whose forum names I can't remember. People have been patient, when payment has been a bit delayed, have wrapped stuff up really well, and overall, I've had some real bargains.
I think the negative experiences are always going to shouted about more than the positive, I mean, someone's harldy likely to start a 800-post thread with 'OMG I bought this X off X, and it's fantastic!', are they?