The client itself is very streamlined. Push/Pull operations are swept into a single Sync operation. Merging is as easy as selecting a branch from a dropdown and clicking a button. Things like that.
On the downside, utilities like tagging, blame and stash do not seem to exist. The account linking system from the old GitHub client hasn't changed and you can't clone from anywhere that isn't GitHub. Revision history is a bit ~too~ simplified and you can't really see at a glance what branches are deriving from where, and you can only see the history of one branch at a time.
I'm sure newbie developers on Github might appreciate the simplified UX/UI, but it's missing a ton of features that are useful in an environment with multiple devs.
There doesn't seem to be a way to do so, but if you open a repository cloned elsewhere everything works just fine. It even prompts for your Bitbucket password if you try to push.