I bought mine (an 88f 8v) when it had 104K on the clock. Original plan was to run it for a bit and get a newer big bumper 16v. THere was a bit of rust here and there but it was pretty much ok mechanically. So I thrashed it around, let the body work slowly go, expecting it to last a few years.
The small bumper look gradually grew on me (specially when you've put some half decent alloys, the twin 5 spoke wolfrace 15'' suit it nicely), and the totally OTT magnex exhaust sounds lovley.
Despite rust now peeking from here and there, and liberal abuse with me

at the helm, the poor old dear is now at 299810 miles

(currently being serviced as I type - everything crossed )
The secret being regular servicing and watching oil consumption (sometimes I swear she was drinking more 10W40 than unleaded) and getting on top of small problems quickly. In fact knock on damage from parts going (such as the water pump, by the time I stopped the head gasket was shot) is the biggest worry.
Other things to watch out for are badgers, rover drivers, and fitting substandard replacement panels (which is where the majority of the rust is).
The only major problem I have is the embarrasment when a well looked after, clean and shiny MK2 hoves into view. Oh and being stopped by the police every 5 seconds for driving what looks at first glance like an old heap!