Having flown the A320 continuously for 20 years and A330 for 10 years with over 14000 flying hours on both types I can honestly say I have only ever had minor issues now and again! The most common being occasional electrical glitches on cold damp mornings till the circuits get warmed up!
Having said that in 6 years of flying the B737 previously, I cannot remember any significant faults on that type either.
Maybe I was just very lucky!
The Viscount however.....now that's another story!