We both have a 335 mine is an 07 with 25 k, my dads in an 08 with 32k. Have not taken either to them yet. Although I did have them give me a quote for installing lowering springs on mine. They ballparked $600 just cuz they were unsure of what was involved. At that price I will just do it myself.
They have worked on my old e36 M, 94 525i, e46 330ci, and a 93 e30. No complaints with the service or cost for any of those.
If anything buy your parts through them rather than BMW.