Note that some bugs and issues are already being taken care of. Please refer to this list before reporting a bug:

Synced category In a synced category wheĐ˝ you are not the owner, shortcuts assigned by another user will also work for you.
Synced category When moving a bookmark from a category to a synced category, there's no notification about the bookmark added.
Tabs bar SHOW MORE button is behaving randomly
UI When moving a category with subcategories from a tab with Tree Categories to a tab with Column categories it will not move the subcategories
Google results FavSync results window in Google might not appear, when Google is redirecting
Sign up If signing up regularly and then using Sign up with Facebook, it will create another account instead of merging with your existing one
Hidden Tab When dragging a catgeory to a hidden tab, the category will be dropped
Tree Mark and Sync category options are working only on the active (currently selected) category

Your bug is not on the list? Report it here.