This seems like a significant release, so it's a shame that there's nothing in the changelog or on the interwebs at large that tells me why it matters. Does anyone know?
Prior to this release, the Mithril team went through painstaking troubles to release RCs to help consumers prepare for the breaking changes and find issues before the official version bump. Now that the code is deemed stable, the 2.0 milestone simply formalizes that the major version bump is now official.