There's not much of an upgrade process. The biggest changes we've made are to the editor and the default template, neither of which affect content. Many of your wikis will be automatically upgraded to our new default template to allow you to take advantage of all its coolness, but you can always switch back to your previous template(s) if you don't like the new one.
We've also added some new plugins to help navigation and organization. In particular, some issues with attachments and moving pages between wikis were fixed, so it's best to wait. Basically, because the wiki upgrade itself is so simple, there's nothing to be gained by trying to "help" it out.