If you have taken the plunge with the Betas, they do plenty of bug fixes with each new version, so it's likely worth it to update if you haven't already. While one of the biggest changes for Resolve 12 has been the editing timeline, there were plenty of important features missing in the first Beta release that have since been added. Here's what's new in Beta 4, as well as the additions in Beta 3:
The Beta 4 update includes new drag Video or Audio only to timeline from the source viewer or Media Pool, still frame mark I/O, a gray UI option in preferences, support for the ARRI SDK for full resolution debayer, improved VU meters as well as general performance enhancements.
New features in Beta 3 include empty track deletion, timeline proxy mode and enhanced H.264.
You can download this update over on the Blackmagic support page.