I have a 2.0 and generally am happy with it, i would have liked a 6 pot but the higher costs put me off. I agree about fuel consumption, in town its crap, on the motorway I have on occasion got 50+ mpg however its usually in the 42mpg area.
Insurance costs were good, cost me £280 for fully comp with protected no claims with admiral.
Had 2 new run flat tyres last month at a cost of £132 each.
Service I had done two months back (oil inspection) which was £230 but this can vary at dealers, the car has a full BMW history and I will keep it that way for selling on.
One thing I would deffo recommend is a BMW Warranty - I paid £366 for mine and its saved me over £2,000 in the past 8 months alone (windscreen wiper motor, vacuum pump, oil leak, exhaust manifold and fuel injector). I bought the warranty mainly to cover me with the roof motor going (which hasnt happened yet touch wood but can be in excess of £1000 to fix).
Generally in terms of looks and running costs I am happy with it. Depends what your budget is and how much performance you want, but i've got 132mph out of mine. As others have said, look for one with a full BMW History.
My next service is an Inspection 2 which I have been told will be around the £350 mark - this is the most expensive service of them all. Generally the servicing is done every 15,000 miles depending on your driving style.