Seems to be mostly done excepting the documentation, which I'd hate to have to write
I'm running 5.0.99.13/rc4 and it seems pretty solid but my hardware is not the newest.
Looking at the last beta announcement, a few cosmetic fixes and as for TODO, documentation updates.
Possibly other things are happening in their lives, once released, I'm sure there will be a flurry of issues, many from not reading and rereading the documentation.