Admitedly, I've only had it for 1 week after trading in my '08 4.8i last weekend.
Drove a 5.0i right before the M, left with the M.
First impression is that it is fast; really, really fast compared to the 4.8i. The power is immediate and endless when you dip into the throttle.
Steering is quite different from the non M.
It's lighter at low speed, tighter at higher speed, wonderful all around.
Suspension is tight when it needs to, very compliant over bumps too.
Overall, a massive upgrade from my prior X5 and absolutely awesome!!
X5M is not a SUV, Not a sports car and not a family car. Then what is it? It is a mix of everything, in another words, it is not great for any of them and it is not bad for all of them. Well, depends on the situation. It is not the greatest sports car, it is a useless SUV and it is a terrible family car. Why did I buy it? I guess I am in blind love with BMW M division. Fuel Economy is terrible but if you have to look at those figures, this is not the car for you.
My family hates this car for its stiff ride and noisy interior, but Nevertheless, I love driving this car more than my Porsche 911, my Infiniti QX56 and definitely my wife's Toyota Sienna.