Been having my four BMWs serviced here during the past four years (528, X5 4.6, M3 and 330) and never had an issue with them. Nathan the owner is really nice and will help you anyway he can.
Great prices all around.
If you want to have Nathan the owner work on your car then head up to the Scottsdale location and his wife Jennifer will check you in. He is extremely thorough so you won't be disappointed.