If you're doing heavy work on a machine as a developer you'll often need to do complex "mousing", such as working in a UI building tool, art program, or working with dialogs in Visual Studio.
For these cases, I find I'm frustrated because I want the speed/simplicity of the touch interface (instead of using the touchpad) but my finger just isn't precise enough.
These situations constantly make me reach for my stylus, which surprised me: Turns out, precision styluses are very useful, even when you're not doing strictly "artsy" things.
However, this Yoga 2 Pro touch display does NOT appear to have precision stylus support. The Sony Duo 13, on the other hand, ships with an excellent wacom-style stylus.
BOTTOM LINE: I think you'll regret buying a touchscreen laptop without advanced stylus support, if you use computers professionally.
EDIT: Others have pointed out the now "Yoga" also released today (not the "Yoga 2 Pro" with the high res screen) has stylus support.