OK, just shifted to WordPress 2.5 (from WordPress 2.3.3) today. Everything works fine – and my fears of having the theme / too many plugins breaking fortunately didn’t come true. So yes, it’s not listed on the official WordPress 2.5 compatibility page, but I can tell you that the ‘Fluid Yellow Black’ theme is compatible with WordPress 2.5.
I like the new interface in fact, although quite a lot of people I hear are hopping mad (or somewhere close to that). Maybe it’s just the reflex webmaster action of having things clunky, but two months of using Vanilla Forums has changed my perspective of how ‘cleaner looking’ software can be much more faster.
The thing I’m most looking forward to is the newer version of the TinyMCE editor – version 3.0 is bundled now with WordPress. The earlier one sporadically used to give some problems, I hope that has been sorted out now. I can only find out after using this for some time whether it has actually improved. Until then, I reserve my judgment on its new WYSIWYG capabilities.