This release have been long in the making so the changelog is a bit intimidating, so we definitely need a lot of testing for this release. I would like to ask everyone to give this RC a shot and see how it behaves with their code and hopefully not find any regressions. If you do find any, please let us know.
I have a problem with the Windows build of 5.2.4 RC2. The extension php_xsl.dll doesn't load, gives a warning (loosely translated) "PHP Startup: Unable to load dynamic library - cannot find requested procedure in Unknown on line 0."