We have had our 2007 e90 328i for just over 3 months and although it handles really well and accelerates the same as an e34 m5, I have a feeling it will be a nightmare once it is out of warranty. One problem with all these newer cars is that the parts are all optimised to only last a short time. Do you know how much an electric water pump costs on an e90? You would be surprised.
Today I got the car back after leaving it for some work yesterday. I took it in because about two weeks ago, I went outside on a Sunday afternoon and all the windows were down, and the sunroof was open. I had not done that.... so I made an appt. to have it checked out. I also mentioned that both the interior hvac fan and the radiator cooling fan had made some weird noises as if the bearings were going. They reprogrammed some module with new software and changed those two fans. All that would have cost around 2 grand if not covered by warranty.
So yes from what I've seen I'd say don't drive one after the warranty is done unless you have deeeeep pockets.
Today I pulled my 2002tii out of storage after not driving it since October 2002. At least when I start driving that I won't have to worry about expensive parts, just where to find any parts I may require!