Beta's for 0.7 are now available
. Please see the Changelog
for a full list of changes.
The biggest visible change is a live preview that can be detached and placed on another screen.
There were also some EPUB 3 enchantments. However, Sigil is still primality EPUB 2 at this point. It is basically EPUB 2 with support for some EPUB 3 features.
Also, Sigil is now using Qt5.
There is a known issue with context menus displaying with corruption on OS X.