The iPhone almost had me convinced that I was writing characters like 门，直，and 辶 wrong. Good thing I was familiar with them before I got it. But seriously, two dots over 辶? What's with that?
I would find app-switching pretty useful too. Right now, if I don't know characters in the test, I've been hand-writing them down, and then using the iPhone's little built in character writer to look them up later.
It's not really much of a hassle, but still would be nice to be able to copy characters straight from the test, look it up, and continue where I left off.