Bought my BMW X5 3.0i SAV in Feb 2010 with approximately 70k miles...current mileage 150k.
I have always thought that BMW hit it out of the park in the looks department when they designed the X5; still do.
I travel a lot for work and the X5 gives me confidence that I can handle any road conditions and is a comfortable highway cruiser.
While I don't regret my decision to purchase BMW's flagship SAV, a potential buyer needs to remember that this vehicle is $50k new and is engineered to high performance/handling specs.
As a result of both of the attributes, ongoing maintenance is going to be more frequent and expensive than most run of the mill SUVs.
It's a BMW....looks, suspension, front seat comfort, highway performance, full size spare, panoramic sunroof, engine oil life monitor, original battery lasted 7 years, and build quality (the doors weigh a ton and close with a solid thud).
The little things, such as the removable front/rear tow hooks.
None of the maintenance has been too bad, with most being preventative and replacement of many original front suspension parts.
Takes a little getting used to having to replace both the brakes and rotors anytime either one fails, but I guess that's why it stops on a dime.
To biggest issues: the air intake tube is poorly designed as can cause a high pitch squeak during low speed acceleration.
If you live in a cold climate, get the oil separator/CCV replaced prior to 100k.
Mine last until 150k, but left me stranded in Fargo, ND - refer to TSB 11 08 03.