This car is simply amazing. I have driven it for ten years and loved every day of it. I am still excited every time I get in the car to drive. Although not a "beast" as far as power is concerned, the '98 M3 can out-handle just about any other car on the road. The ride is adequately comfortable, yet the suspension gives every turn a sporty feel. For the most part, this car has been trouble-free (albeit only 55kish miles; water pump, clutch replacement). Some minor complaints: wish there was a 6th gear, fog lights seem to crack easily, poor air conditioning.
No major mechanical problems at all. The handling in this car is unsurpassed and inspires driving confidence. Despite entering curves at very high speeds I have never felt the car couldn't handle it. The only minor criticisms I have is the rather bland interior and the ridiculous cup holders.
Bought it new and haven't regretted one day of ownership. Tracked it a Buttonwillow in California and that was what made me a believer. Before that I thought I just had a nice coupe. It has unbelievable handling. As the driving instructor said, don't change anything on the car. What needs to be modified is the driver. Been very dependable overall, but there have been many owner fixable repairs, if you are handy. Door panels will need to be regaled if left in hot climate, cooling system is actually not bad IF you change the cooling fluid every three years. Warning! If you put Bilstein shocks on, yur spouse may think the ride is too harsh. Have no plans to sell.