I keep a SVN based copy of the new WordPress 2.5-beta1 for playing with. I’m doing this because at sometime the version I’m running 2.3.x might not be supported for patches. Going from 2.2 to 2.3 was a no brainer, tags are a huge difference. 2.5 might not get me to jump for a while.
On the outside I can’t see much reason for not converting. Some of my plugins don’t work but that ought to be resolved by the time 2.5 is released. If the performance is improved then that’s a good reason right there.
What will get me to hold off is the little things. I dislike the new interface. The 2.3.x shows it’s age meaning that it is well thought out and is missing some pet peeves from 1.5 or 2.0. Version 2.5 feels like they are trying to get to “Web 2.0” and are not making it. The organization is odd after using WordPress for a couple of years. The widget interface is downright counter intuitive for me.
I’ll keep using 2.3.x for a while and just see how 2.5 turns out.