I have experienced jerkiness, and it takes getting used to to get rid of. I have only driven manual cars for the 10 years that I have been driving, so the SMG was a change for me. I prefer a 3 pedal manual, as I don't track the car often enough and don't get stuck in traffic where a clutch would annoy me.
The biggest pain to me is trying to get the heel-toe action down on downshifts, especially to 2nd gear...you have to hold the gas pedal down for the car to blip the throttle, not just blip it yourself, which is counter-intuitive in a 3 pedal manual car when heel-toeing.
Opinions will vary on this, but the SMG is enough to make me want to trade the car for a true manual. I have been looking at e39 540i6 cars for a little bit and I will probably go with that. Take my $.02 for what it's worth, but I would think that people who love driving 3 pedal manual transmission cars will not enjoy this transmission very much unless they must have an auto or semi-auto car [for the wife, traffic, due to a handicap, whatever reason].
My advice to anyone considering an SMG is to spend as much time in it as possible prior to making a purchase decision.
1962 Porsche 356 Coupe Champagne/Black
1988 Porsche 911 M491 Cab Granite Green/Linen
2002 BMW M3 Coupe Carbon Black/Black
1992 Porsche 968 Coupe Black/Black
1997 Porsche 993 Coupe Arctic Silver/Black
2001 Porsche 996 Coupe Black/Black