I don't think you can argue that BM know how to make good cars, and their engines are amongst the best in the world. In fact, their chasis and engine men are so good that Audi (well VAG) poached a couple to work on the RS4 and R8 (BM has since poached the chassis man back!).
I don't like the shape of any of the new BM's, particularly the 5 series and above, but I don't doubt that they're excellent cars, and you'd have to be a good driver in a similarly spec'ed to car to get the better of them. There's a reason that they're so popular.
Plenty of people tune their BM's - you can bet that there'll be a host of well researched, well supported aftermarket upgrades for the new TT beemer very shortly, and believe me, it's amazing how much difference even a few psi extra boost make to a turbo'd car.
I also think that the badge conscious (many BM drivers I suspect) end up missing a lot - I'll stick with the Z and the VR4, and maybe one day I'll have the cash for a skyline or an RS4!