Occasionally when you click back to focus Chrome, your focus stays in Hangouts, then you can't use Chrome's keyboard shortcuts, as you are in Hangouts instead.
Otherwise, hopefully this works better than the old extension - when starting Chrome it kept not logging in without being disabled then renabled.
Also, why the big white box on start - couldn't that be the contact list?
I'm getting the focus issue as well (I get it sometimes with the old extension, but much more with this new one).
Also, there seems to be no notification at all when someone messages you. That makes it fairly useless as an IM app. At least it doesn't pop a full conversation up in front of you like the old extension did.
It also doesn't seem to support multiple accounts (the old one didn't, either).
I don't really find this to be an improvement over the chrome extension in any way, it just doesn't seem like it's finished.