I just upgraded a bunch of my blogs to WordPress 2.8 using the built in “Automatic Upgrade”, and as with any other update I were scared to death that something would break and I would have to spend the rest of the day reverting back to 2.7.
Fortunately nothing bad happened, as a matter of fact, nothing really changed, and the only change that I have noticed is the option to change the number of columns you have in the backend.
Customize how you view the backend in WordPress 2.8.