I have had an X6 for the last 3 years. It was the V8 twin turbo, every option. Overall a very comfortable car. Very quick and handled well for a big car. People either love them or hate them, some people not into the shape. I liked it from the first day I saw it.
The only problem I had was electrical, it would always drain the battery and then I could not watch the TV or listen to the radio if I was parked anywhere.
Just traded it in 4 weeks ago on a new car, no regrets.