I was in the first batch of Smart owners (pickup in January of 2008). Have had the car for almost 14 months now with 20,600 miles on the clock. It's been my principal, daily driver. Averaging 46-47 MPG on my 60 mile daily commute (40% Hwy and 60% suburban).
No problems, no issues, no complaints. I'd buy another one and am recommending it to others.