If I exceed 200 characters the behaviour is a bit disturbing. The comment field scrolls all the way to the top. Is there another way of catching the verbose user? Perhaps providing feedback somewhere on the number of characters used to date?
Under normal conditions (someone types 3 or 4 lines of text) it isn't reproducible. However, if the user uses 5 or more lines for the feedback, e.g. a bullet list of points, then you see this side effect.
I've just tried this in Chrome 11.0.696.71 and FF 4.0.1, and neither of them did anything unexpected when reaching 200 chars (it can't go over 200 anymore).