There seems to be some issues preventing the comment form from operating smoothly on some systems.
I am running:
Mac OS 10.6.2
This may be a general issue with webkit browsers.
When hitting preview, the script takes a very long time to load the preview. Somewhere around 30-60 seconds. This might be by design to encourage people to actually read their comments, but it doesn't feel quite right.
Also, when the comment box loses focus, it cannot be reactivated by clicking on it with the mouse. The only way to reactivate it seems to be clicking around until you can highlight some text in the comment box and then use the arrow keys to position the cursor. It's as if the clickable area of the comment box does not match up with the location that is represented on the screen.
Use above operating system and browser version, log into an account, and try to place a comment on a story.