Although I have only just upgraded to Plone 3, I have already experienced some of the benefits of having done so. Many of the features I had read about and anticipated. I had been using RichTopics which has gone from being a standalone product to a feature, in Collections. But Live Search, the buildout function, and improved editing interface make all the self-inflicted hassle worthwhile.
Admittedly, my initial experiences with this were not ideal. But one feature I love on my Debian and Ubuntu machines is the automatic updates of applications, unlike my Windows machine that only updates its own OS. Now, when I list an egg in my buildout.cfg file, and run the buildout command in the future, it will keep that product up to date without me hunting down the latest version. Sure, it’s lazy but it is more likely my products will be current for future migrations as well as feature benefits.
The 2.5 interface was’t terrible but I love having the editorial tabs for categorizations (was properties) and settings, among others, pushed down into the document more, showing that they are hierarchically different from view, edit, and supplemental tabs like SEO: they all impact this document’s editing.
It took me a while to find the related feature where you can cross reference files on your site, under the categorizations tab, but the feature works so much more smoothly than it did. I would love to be able to grab multiple documents at once but that is a minor issue.
All in all, I am glad I made the migration to Plone 3. I do not have the programmatic chops to contribute or develop in Plone, but it is fun to be able to use this enhanced interface.