The x5 is a great car, it has not broken down once. I am amazed it can do over 161 mph. It also has an amazing crash test rating.
The i-drive system is great, it could not be better. I own a 2006 Audi A6 and its computer is easier to use than my 2007 BMW 5-series' computer but my 2009 X5's computer is easier to use than both of them.
The fuel economy needs a bit of work because it gets only 12-16 mpg which is not the best.