I bought my Xterra with 4wd used in 2010, and have since had it for 2 and a half years. It has been a fantastic vehicle in terms of reliability and performance. The problem is the gas mileage. If you do not need to haul heavy things, pull large objects, or you do not frequently encounter bad weather, then I do not suggest this SUV. The back seat is cramped for adults, and the interior lacks a lot to be desired in terms of comfort. Combine those aspects with the very poor mpg, and it makes this SUV difficult to validate. HOWEVER... if you do need such a vehicle, I could not suggest a better one. The reliability is up there with Honda, and off road/ working performance is great.
The traction control system is great, it can handle most basic bad weather without you needing to turn on the 4 wheel drive system. If you do need the 4wd system, then you still don't need to worry because the system is straight forward to activate, and works great. The interior is very lackluster, but very durable. It holds up well to wear, and is easy to clean. The cargo space is deceptively spacious, especially if you are a Tetris wiz. The roof racks are solid, and can hold a stand up piano (speaking from experience). The exterior looks are masculine, but not ugly. The seats are supportive enough, and visibility is quite good. Turning radius is good for a car of this size.
Again, the gas mileage is poor if you are looking for a daily driver or family vehicle. The interior has virtually no 'toys' in a base model. The back seat is quite small. The V6 engine is powerful enough but whiney when pushed. There is plenty of power off the line, but it has trouble finding any extra at highway speeds (which just means it is not super fun to drive). The body rolls a bit when turning. Did I mention the gas mileage? But honestly, it is a great vehicle for the right people.