First thing, I have only had this car for a month or so therefore I haven't really given it much chance to break. I didn't really go looking for an X5 - I had two 5 series saloons previously that were great, but needing to transport a couple of dogs and some musical equipment regularly, I really wanted an estate. 5 series estates are like hens-teeth, whereas the X5 is reasonably common, so that's what I ended up with.
After the 5 Series the X5 feels big. It isn't that much bigger in real terms, but the seating position means you can't see any of the edges, which makes parking in Tescos interesting - hopefully I'll get used to it. Don't get one without parking sensors!
The interior is more-or-less stolen straight out of the E39 5-series. In some respects that makes it a bit dated, but on the other hand, it was one of their best interiors. The dash doesn't curve towards to driver like the saloon does, and that makes some of the more distant buttons a bit of a reach. It doesn't feel quite so driver centered either. Other than that, it's pure BMW comfort and quality. Practicality is good - good sized boot area and seats that fold flat.
Mines the 3.0d Sport - they nearly all are. It's more than fast enough, especially considering the weight. The suspension is a bit stiff and that does make the ride a bit bouncy. Despite what people say, you won't forget you are in a big 4x4, but the ride is impressive nevertheless. I've been driving around in the snow, and considering it isn't a "proper" off-road vehicle, it gets me places a 5-series saloon never would have.
If there is a disappointment it's the automatic gearbox. I've been doing some looking around on the Internet and I don't think I'm alone. It's a 6 speed self-learning job, and frankly, it's a bit stupid. The change is not as smooth as I would expect, and having 6 speeds just means that it changes a lot. Around town it results in a rather uneven ride. It can be very sluggish sometimes, particularly a junctions when you don't want it to be. When you hit the gas and nothing happens, it's very disconcerting. The reaction is to hit the gas harder and that just means that when it does change you get "slammed" out of the junction. Not good enough for an expensive BMW. I guess I'll learn to drive around it, but I shouldn't have to.
A very good car all in all, only marred by the sub-standard auto transmission.