The site ran flawlessly right away, with its 25 plugins including Wp Super Cache, the YD Recent Posts Widget and some other quite vintage legacy plugins that I can’t do without. I had no special migration task to conduct. I even ran the site for a few hours on a staging URL without upgrading the database structure, and did not notice anything breaking.
As far as I’m concerned, the greatest improvement in WP 2.8 is a very important bugfix that makes multi-parameter queries work: up to there, you could not combine a Category search + a Tag search (WP core trak ticket #5433). The bufix had been available as a patch for a while (I had patched the 2.7.1 powering the post2peer.com content sharing site and it did the trick), but it’s always better to have the fix included in the official release.
I am running quite elaborate queries combining post and tag exclusion on the www.Nogent-Citoyen.com site, that did not work with the previous WP 2.1 version this blog was running on up to recently. Now everything works as expected so I can do away with the elaborate strategies I had to develop to get around the bugs. This straightens up the code and makes everything simpler to maintain.
I did not notice any performance improvement with WP 2.8 compared to 2.7.1, but then again, running WP Super Cache pretty much hides any performance issue or gain.
Two thumbs up to the WP core team for this fine running brand-new release. As far as I’m concerned it’s already in production, so just go for it, guys, move on!