I haven't upgraded and I won't. 247 with all my improvements is good enough for me. Having said that, I'm now starting to fix quite a few things in 332. The lack of "add code to post" will be fixed, in addition to "float left" and "float right" along with add code.
Mandatory avatars (a 'feature' now) will be removed before I use 3.anything on a real server. I *might* make it an option, but I doubt it as there are at least three avatar plugins that give the owner of the installation better implementation methods and control than the mandatory POS in the core.
In 331 anyone and everyone who can post at all can post a ... I forget the name but a post that stays on top for certain types of page displays. Like a category post that you might use to describe the category. Neat idea, except anyone who can post is allowed to select that post type even if there is one already. The other one never shows up. It might have been fixed in 332 but since I haven't played with it yet I don't know.
The list of crap in 3.* is amazing. Footer spam is still there (of course), as is the spyware that is triggered every time you hit an admin page, and the splog links. Now you get context spam if you enable a 'feature' in the auto-link plugin. Another "feature" that no one asked for that was already possible with a plugin, only this feature has no easy way to see what it will link or control it via your back office.
I'm also thinking I should make something that will fix a 331 or 332 installation by upgrading it to my 2471.
Just my opinion though. I'm sure others just love it.