My car has StepTronic and its nothing like a manual
but it can be fun.
I use it for burn-outs because it locks the torque converter, I can get some wheelspin that way. Having a torque converter locked in 1st gear while driving around residential areas without traction control while keeping the engine in the 5,000-6,500rpm range is quite fun. The car reacts to any input very violently (as in, it makes your neck hurt after a while), its awesome.
I've never used it for passing, I simply use the kick-down switch for that.
The StepTronic manual mode is most effective when traction control is disabled, once again because the torque converter is locked. Drifts and powerslides happen naturally.
Normally there is annoying lag during shifting but I've found that if I lift my foot off the throttle just enough, the shift will happen very quickly and smoothly. Same goes for downshifting. If I downshift without giving the engine any power, the car will jerk forward, the tires will screech and the car will begin engine braking. If I give the engine too much gas when I downshift, the car will jerk backward as if it was getting ready to catch some speed as the engine revs to 5K or so. If I give the engine the perfect amount of power while downshifting
and get the timing right I can make the car downshift like a manual with a nice throttle blip. Its great.
I want my next car to have SMG, but for now StepTronic does the job.