The X5 has been outstanding. I've got the sports pkg and performance pkg. The 4.4 engine is a must for this heavy, solid vehicle. Not only is it powerful, but it sounds great. I was looking for an SUV that acts like a sports car and this is it! My wife calls it a motorcycle on 4 wheels because of its performance (I ride sport bikes). I've only owned it for a few weeks and I just drive it around for no reason because it is so fun. I average around 17 mpg driving it hard. It actually gets the same gas mileage as my previous SUV that only had a 3.5L V6. This is my first BMW and I am hooked.
Performance, handling, comfort, looks, engine sound. Oh yeah, I am 6'3" so I really like the thigh support in the sport seats.
Weak stereo system and near impossible after-market audio integration. Still not used to the console layout for things like cell phones, wallet, etc.