Stylus is great for stabbing at the keyboard, but not so good for drawing quickly.
The nib is simply too soft and drags on the screen.
OK for using on the Android soft keyboard in 4.1 and earlier, but not so great on 4.2 (with the swype style keyboard) and definitely performance drag if you use Graffitti (yes I am old school). I've gone back to using my finger unless I'm demonstrating to someone and therefore moving slowly and trying to keep the screen clean.
Edit: I had a brainwave, cover the tip in cling film. It works and I've stopped looking for a replacement!
Windows Phone 7
Nexus 7 (4.1 and 4.2)
Xperia X10 Mini pro with CM9 (don't bother the screen's way too small for this stylus :D ).