If the device is plugged in, Handwriting and the on-screen keyboard more or less work fine.
If the device is running off battery:
The on-screen keyboard lags terribly, usually taking a second or two for each character to display.
Handwriting works for a handful of characters, but then rapidly stops recognizing the strokes made on the screen. When this happens, the system tray begins to flash very rapidly, as if a process were dying over and over again. Usually this behavior slows down and stops, and you can start drawing the next character or two, before it starts all over again.
Of course, I usually on ever need the handwriting when I'm running on the battery. That's the dilemma.
Edit: One extra item of note. If I detach the screen, it seems to work fine as well. So it seems to happen when the computer is in "studio" mode.