Got a great deal on an '06 X5 and took the plunge purchasing my first BMW. It's amazing how smooth and quiet the vehicle is at highway speeds compared to the Ford Explorer and Jeep Cherokee I owned previously. Granted, the tires probably have a lot to do with that, but engine and wind noise are way lower too. Love the grunt that the 3.0 inline six delivers--it loves to rev!! I was a little concerned about the gas mileage, but it's been a big improvement over the Explorer, getting 23 or 24 mpg for pure highway driving. Premium unleaded can get a bit expensive when prices are up and synthetic oil drives up the cost of oil changes, but so far I'm dealing with it and loving the way it drives!
Heated seats and heated steering wheel-- love 'em, love 'em, love 'em!! Materials used seem to be of high quality throughout the vehicle. Drives and rides great!
Cargo capacity is compromised by the shape of the hatch. Lots and lots of brake dust means cleaning the wheels frequently. Large pillars make for large blind spots when driving. Flip down sun visors are kind of cheaply made compared to the rest of the vehicle and don't swing fully to the side.