The 8sp box is the smoothest I have ever had the pleasure to drive. The shift pattern is a little (but only a very little) different when cold, as all autos tend to be, but once warm then it's a beauty. Very quick shifts (less than 0.2 sec) and if accelerating away you just don't feel them - which can mean you are past the 70mph limit VERY quickly and without noticing. ZF say it uses only two active shift elements when changing gears rather than the up to 5 on the 6sp.
The transmission is supposed to be capable of shifting from 8th to 2nd in ONE step, and it certainly uses 'block shifting' when required. Using the paddle shifters in full auto is useful as you can fast shift a number if gears. Not sure if the X5 has them. Kickdown is very responsive. Having got Bimmers with each box fitted, the 8sp is a beaut and it was what made me go new rather than nearly new when I bought the X6. That and the 40d engine of course......
