iOS (and maybe other capacitive touch screen devices) reject inputs that are less that 30px (or something arbitrary roughly fingertip sized like that) as noise. This is why you can't have a tip the size of a normal pen. Also, many people write by keeping their hand resting on the sheet of paper which is interpreted as either an input, or a single touch of multi touch (think pinch and zoom with fingers on each hand).
Therefore, to write on an iPad is more like painting or writing on a whiteboard and less like writing on paper. While tons of people are very talented and able to sketch and paint on iPad with no issues, I find it more difficult than writing on pen & paper. Something like the iPen removes some of these obstacles, though it seems to still be in the early phases.
It's not that I can't do it with a stylus (I have one from Boxwave), its that it isn't as quick and easy as an actual pen. I was hoping iPen would close that gap.
