I bought my 330Ci used. Its a 2001 and I bought it when it was 5 years old (built 11/00). The mercedes dealer who took me for the test drive could not believe the car was 5 years old, it handled like it was brand new. No rattles, no engine roar and no wind noise with closed windows. When one of these new cars with more horsepower that keep comparing themselve to bimmers gets to be 5 years old and feels fresh off the showroom floor, I'll be impressed by them. Until then all I can say is nice car. But I have no reason to think its a better purchase than a Bimmer.
You can't just put a powerful engine in a small car and think you can take on BMW.
Another way to look at it is that if they are making that low price point they have to be cutting corners somewhere.