It's very hard for some of us to know what's a bug and what's intended behavior. For example, in virtual mirror, each edit operation switches the symmetry side. To me, it seems like a bug or an April 1st joke, but maybe it's intended behavior? That said, the beta is quite good, in some cases even less buggy than "stable". And I understand the challenges of testing a complicated piece of software, specially one that includes so many user-interface elements.