I swapped two bikes to the newest SRAM Red 10-speed last year (Why have you forsaken me SRAM?!) and couldn't be happier with the performance. The new group is well thought out but the front derailleur and cassette are the stand outs of the litter.
The way the first generation "powerdome" cassette was engineered made it a defacto drum and the level of noise produced could be disarming to you and other riders. SRAM went out of their way to make this the quietest cassette known and it is. I love hearing the wurr of a well oiled chain and now I can.