Hey Ben,
I've upgraded my devel server to 5.2.0. The core is great and seems reasonably solid. It adds some extra super cool stuff, like a developer toolbar (maybe it was there in 5.1.5, and I might have removed it in my pages before I knew what I was doing, but I don't think so). It looks like user profile pages have seen some nice updates. I can hope, but haven't confirmed, that user portraits now use the content repository in legally sanctioned ways so it won't break classified-ads and other users of the content repository.
But, and it's a big but, 5.2.0 has no packages. Ok, maybe one or two. Ecommerce is quite broken on 5.2.0, and probably won't work for some time. Forums work well, as far as I can tell. Bug-tracker works. News seems to work. The book reviews package is broken (package_id problem). FAQ seems to work. Voting is broken (package_id problem). I believe that's all I'm using, so I can't say much about any other packages--but the "install from repository" page lists no packages, and so it might be that even the packages that work can't be installed for 5.2.0. (I'm unsure how any of that stuff works, so I may just not understand how to see what is available.)
It seems a lot of functions have been deprecated, but many packages have not been updated to use the replacement functions. I'd like to start bringing them up to date, since I'm going to be doing several new developments on my OACS site and I'd like to do it against the latest codebase, but I've been unable to find any reference to tell me how to go about updating the broken code.
Anyway, I won't be upgrading my production server until ecommerce has been fixed at the very least. I'm betting that if I devote a weekend to it, I can figure out how to fix the package_id problem packages, so ecommerce is the real deal-breaker.
