Just sharing my experience with my new 2.8 X3. Have about 1300 miles so far and about a week ago I saw the oil sensor malfunction error code pop up. I was still able to check the oil level, which sometimes take a minute or so. The problem has gone away completely and I haven't driven the car hard like some have suggested in this thread. Going to have BMW check it over in a few days.
Otherwise, the X3 is flawless. Love the tranny.....it shifts very smooth. I especially love the heated steering wheel.....of all things.
One thing that is a little overwhelming is the level of electronics. I have the navigation system and it's taken me a while to get used to all of the technology. I still learn things everyday. Of course my previous ride was a 1999 M3 and it's technology was very limited. But, it had a dipstick which I loved.