Passenger side window fell off inside the door (poor clips) fixed this myself with some tie straps.
Exhaust backbox replaced (£30, to be expected).
Catalytic converter replaced, (£110, plus £40 labour) - nothing actually wrong with cat, the flexi joint up front broke.
Damp passenger side footwell (common on polos) due to a failing door seal. Again, easy to fix.
Great little car for run around. Easy to repair when things go wrong if you are a bit handy with cars. Decent interior, fair bit of space in the back (i have 3 door), no real signs of wear yet.
The paintwork however is starting to deteriorate and my rear wheel arches have started to rust. I would like the car to be faster as I'm a bit of a speed freak, but that's it. If you are after performance, go for a 16v model.
I find the mk4 Very fast as I have converted the 1.4 engine by boring grinding and tinkering I now smoke 2.0 civics and various other well tuned cars.