I've been driving my '09 128i since October of 2010.
In that 2.5 years I've only put about 17-18,000 miles on it.
I make a lot of short trips so my average mpg of about 18 is a little disappointing but not real surprising.
The car is a little hard-riding and the stock seats are not particularly supportive or comfortable.
Those are probably my two main complaints with the car.
Reliability is a concern, too: replaced the lifters, the a/c evaporator, the radio, the third stop light, etc. Thankfully this has all been cheerfully replaced under warranty. This is all balanced by the gem of an engine, good visibility, good looks, solid handling, etc.
I do love the little, fat, steering wheel!
Engine, brakes, handling, folding rear seats (I am a homeowner and do have to haul stuff home from the home center on occasion).
More practical than you might think.
Back seat is OK for adults for short trips.
I don't need to feel EVERY imperfection in the road surface; a little suppleness in the ride would have been very appreciated.
I ditched the run-flats for "normal" Michelin's but the ride is still an issue. It needs better seats, too. More comfortable and better bolstered. I'd like to take the seats from my old Passat and put them in this car!