A bit late for this now but It had just occurred to me that the option of being able to preview how your posts will look is gone. Unless this part of how this new upgrade works, I feet that it something that should be added back again. it was useful in making sure to make any last minute corrections to the posts before actually posting them instead of constantly having to edit them over and over again like we have to now.
I concur that. Mostly because of this whole double-space deal. I know Ordos threw in a patch to remove those when you hit the Submit button, but I keep forgetting about it, resulting in most of my posts being a single block of unreadable text. It's really annoying. Would be cool if either a proper preview feature could be brought back or a proper fix for these Reply-Box oddities.