Start-stop and autobrake on the Superb (with DSG) works like this. Start-stop is enabled by default at startup, you can turn it off but this is forgotten when you turn the ignition off. Auto-brake (handbrake) is disabled by default at startup. With start-stop on and autobrake off (default setting), when you stop the car using the footbrake (or just before) the engine cuts out, and stays that way as long as you have your foot on the brake. When you take your foot off the brake the engine restarts, and (in a TSI) is running by the time your foot can press the accelerator -- result, no delay (may not be same on TDI due to longer cranking time). The car also has hill hold so if it's on a slope the footbrake stays on after you take your foot off it and releases when you press the accelerator to move off.
If you turn auto-handbrake on (switch on centre console), the engine doesn't restart when you take your foot off the brake, it only starts (and handbrake releases) when you press the accelerator -- in this case there is a noticeable delay which I agree is dangerous.
For TSI engines which restart quickly (and start and stop without a judder) there is no delay or annoyance with start-stop only, this was the case for my previous TSI220 and current TSI272.
For TDI engines which restart more slowly (and also with a noticeable judder IIRC) there may well be a delay as other people have said.
So the problem is not start-stop as such, it's start-stop with the TDI engines. It works fine with the TSI engines which will also consume a lot more fuel at idle than the TDI, so start-stop could make sense for these. With the TDI engines with much lower fuel consumption at idle (no throttle), slower starting (longer delay), and more noise/judder when starting and stopping, it doesn't make sense.
What is really annoying is that like many other things (e.g. driving mode) the Superb no longer remembers driver-selected options next time it's started. Maybe this is now mandatory to avoid manufacturers fiddling emissions tests by secretly enabling "eco" options instead of standard ones (so VW could be to blame...) but it's really irritating -- for example I always want DCC to be in sport mode (less bouncy) but have to select this every time I restart the engine :-(