The beta went out 4 months ago, and the 1.3 roadmap wiki page says to check the mailing list, but I didn’t find anything there. I’m guessing this is the new version of the mailing list, so I thought it would be a good place to ask.
A lot of the current issues are focussed around getting an effective migration path from 1.2 -> 2.0. See #2918 for an update there. Patches for full Windows support have also been going in, in preparation for the next beta.