After using for a while the new WP edit form (not the ugly WYSIWYG obviously but that's another story) I decided:
The most annoying thing (well, aside of having to empty the cache and restarting firefox every time I want to upload a picture) is the location of the category list.
It is a bad one because I want to verify the category right before saving and especially publishing, but the list of categories is out of sight, down below the page. So I have to scroll away from the button and then come back. (I use 20 lines for the post box. I want it to fill most of the page at least in height, so that I can write with a bigger screen font. The page is about writing after all.)
Was the publish button still at the bottom too, I could cope. But now it moved to the top of the page, which is cool: it probably wanted to stay closer to the categories and guess what? The categories moved.
And what with all that empty room below the buttons?
When WP introduced the tags I hated that line that read, I don't know, something about "cat food" or whatever, which sounded so disturbing when I was writing maybe a very serious post.
It was so annoying I wrote a plugin only for myself to get rid of it.
Guess what, that "related" box introduced with WP 2.5 below the save and publish button, where many other more useful things could be, is the new "cat food" line to me. It is useless and annoying, good only for newbies.
So I just made myself a dedicated plugin only to remove it, how about that.
One more annoying thing: are really full-width blue lines needed to specify which one is the title and which one is the post? Seriously? Couldn't a "title" label next (not above) to the title input suffice?