Im buying one on thursday this week all being well, test drove it last week. There a very nice quality car with lots of nice bits and pices to look at and keep you interested in it, they go fairly well i would say similar to an e39 m5 and a bit more than an e46 m3, very tourquey engine that love to rev hard and pull best at the top end, make a great noise.
From what ive read there pretty reliable, with main issues being the valves and inlet getting cabon build up, the drc suspension can fail and the inlet/airbox and exhaust flaps stop working. I guess there expensive to run in terms of parts prices but youve gotta expect that with any car at this level of performance.