I use this feature when I'm in LA almost constantly, knowing you're not wasting priceless fuel when stopped at the light does give some relief. I've learned a trick to make this feature a little more fitting to my preferences (this is applicable to m3's equipped with dct). For example, when you come up to a red light and you know it's going to turn green any second, or it's a situation where you may need to keep inching forward (stop sign), I fully stop the car and then release the brake. This keeps it from turning off, but obviously the surface has to be flat and the brake should be covered. It takes approximate 1.5 seconds for it to turn off with the brake fully applied and the car stopped. I wouldn't recommend using this feature on freeway traffic unless your not moving at all for extended periods (I don't usually make the motor turn off unless I anticipate sitting for 10+ seconds).
I disagree that this will cause wear on the motor, if it is it's negligible and the motor idling causes just as much or more. The wear item from this feature is the starter, and BMW has equipped cars with this feature with heavy-duty starters to compensate for it.
As far as the time it takes to start back up and go, it's really nothing. You don't have to let the RPMs settle after the restart, you just give it gas after the I initial start and the clutch enacts and your off.
'00 M5 - Sold
'08 335i w/m3 conversion - Sold