Besides my earlier post where I complained about the Widget/Sidebar interface, I have also found three people now who did not have their upgrades complete for some reason. It appears some files, specifically in the wp-admin folder, are NOT getting copied over on the first attempt.
If you see something flaky in the Admin Section (missing buttons, garbled screens, etc) then download WP 2.5 again (to make sure you had a “good” copy of the files) and then re-copy the files to your blog.
Also, Windows Live Writer, which was working fine before the upgrade, now gives me an error when I post. My post IS published to my blog, but WLW makes it appear as if it hasn’t been. I’ll look into this more later.