I installed version 5 for Windows and have not experienced any problems with it nor with syncing music and podcasts to my iPod Mini.
Nevertheless, clearly there were issues with version 5, so Apple has now released iTunes version 5.0.1. Note that the version change is not mentioned anywhere on the download page.
As I haven't experienced issues, I'm sticking with 5 for the time being, as from the many posts in the Installation & Upgrades Forum at Apple Discussions, it looks like 5.0.1 either doesn't entirely fix the issues people experienced or introduces new ones.
(Hat tip: The Apple Blog)