The following quote from the article sums up the X6 very well:

"Despite all the clever engineering, it still manages to artfully combine all the disadvantages of a tight-fitting coupe with all the downsides of a big SUV. The result is a vehicle that can't go off-road or carry as much stuff as a regular SUV and doesn't quite go around corners as well -- or use fuel as efficiently -- as any comparable BMW car.

I guess the point the X6 proves is the auto business has long ceased to be about transportation. The auto business is really a fashion business. The X6 exists only because BMW's marketing mavens are convinced there are enough of you out there who want an SUV that thinks it's a coupe."

I went to the BMW dealer yesterday and saw/sat in the X6. The rear feels tight and the trunk is a joke because of the sloping roofline (much like the CLS). I personally think the X5 looks SO MUCH BETTER externally (just my point of view) in real life. In fact, the X6 borders on being ugly (especially from the rear and rear 3/4 view). The side profile is also awkward because of that super sloping roofline. I think the press pictures really made it look better than it really is.

It is basically an SUV that has lost all of its practical features (rear passenger room/luggage space) for the sake of style (if you actually like the external styling).