I think I've been lucky with mine and haven't had any real problems since new (bought it in May 2000) and covered 22,000 miles.
Problems I've had are:
Excess wear on Drivers fabric seat cover - replaced by dealer under warranty.
Button on driver's door handles get stuck in occasionally - bit of WD40 every couple of months sorts that.
Uneven tyre wear - full geometry check - £50
Squeaky roof lining - turn radio up.
Some Twin Spark engines get through a fair bit of oil, but I haven't added any ever and it's still full on the dipstick.
On the performance side,
I run mine on Optimax and have replaced the filter with a K&N one and the performance is good, but am thinking about carbon fibre air intake or rechipping.
Note: Power dropped on the 2.0 TS engine from 155BHP to 150BHP sometime after MAY 2000.
Kristian (156 2.4JTD 140BHP)
On my 2nd Amazon Green