the 7G tronic gearbox shifts and performs really really good, the problems with it usually were the EGS (electronic gearbox system) module. The painful part here is that its part of the valve body, the good news is that MB now sell it separately too - previously this was a 900 Euro part complete with valve body - now its a 300 euro part - but it can only be written via a STAR unit after it has been installed in the vehicle.
To fill it you need to buy the fill adapter or make the fill adapter. Meaning that it has no topside fill port (like the dipstick pipe on older ones) - this one is filled from the drain port - the correct level of ATF is measured from the same fill/drain port - the port has a piece in it that causes the sump not to drain at a certain level. It is measured at ATF temperature only and immediately corrected.
the SBC brakes have a timer built into them that expire and will require a new SBC unit - If the car is equipped with SBC and your mechanics are not familiar with this system - please study it and show them how to take safety steps - the SBC will engage and operate the brakes when the pads are being changed unless it was disabled.
It has great force and can completely cut off fingers if they get caught in the calipers.