Paddington

I am thinking about buying an Audi 90 (5-speed, 130k) to use as a commuter.
The car in question is a blk/blk 1995, with service records dating back
quite a few years. I haven't looked at it yet, but I thought with this
groups help I would be more prepared when I check it out. I am well versed
with German cars, water cooled Porsches specifically, so I know the obvious
stuff like cam belts/water pump, etc etc. What i've been told so far is
the car has a converter that rattles and the speakers do not work, but
otherwise looks/runs good. Asking price is $3500.

What should I look for?
What are the notorious problems with 90s?
In general, are they a well built & reliable car?

Thanks!