I personally don't care for real leather as long as the alternative is good. In this case, BMW's leatherette works fine, it's lower maintenance, and more durable than leather. However, if you want to get certain options you will need to order leather.
BMW Assist is a seperate option that is included for 4 years if you buy Premium package or the a la carte BMW Assist/Bluetooth option. Personally, I think BMW Assist is useless, having not used it a single time when it was provided on our X3. We just let the subscription expire.