I've only been using this for less than a day, but I am already getting very annoyed at the fact that waiting a short time before clicking a link (including following a tag or submitting a post/comment) means I get a timeout and redirect to /deadlink. So, I have to hit back, copy my comment/post to the clipboard, refresh the main URL, paste the comment/post, then click submit.
All the important data should be stored and signed on the client so that it can be resent whenever needed instead of server-side timeouts. Of course, this is theoretically prone to replay attacks, so it should only be done for cases where the client could meaningfully intend, or the server could easily ignore, a replay, e.g. following a tag or accidentally making a post/comment twice.