I have a M3 wheel on my 135i. I love it. The leather BMW uses is a bit hard(& rough) to the feel/touch. I used some "leatherique" oil to treat the leather bits on the steering wheel. That really softened up the leather and gave it a "nice" feel to it.
I really recommend you guys to buy a bottle of "leatherique" oil - its about $30 but worth it. The leather feels so much nicer now.