Review: Samsung Nexus S
For the most part, touch response on the Samsung Nexus S was flawless, though some apparent bugs in the system did cause problems with the touchscreen. After my initial startup, the phone was a bit laggy to the touch, but that's because Android downloads and installs all of the apps I use on my other Android devices, and app installation tends to slow down the phone considerably. Once my 40 or so apps were installed, the phone responded more smoothly to the touch.
A few times, though, the touchscreen simply stopped working. I would swipe the screen lock to open the homescreen, and that gesture worked fine, but once I was looking at the homescreen I got no response. App icons and shortcuts would not register my taps, and I could not swipe from one homescreen panel to the next. It was very disconcerting. This always cleared itself up after a couple minutes, so it seems more like a serious system bug than a problem with the touchscreen. Thankfully it never happened during my phone calls, and hopefully a future software update will clear up this problem.