We use hangouts at work to do code reviews, meetings and generally for voice communications. Its great.
But when screen sharing, the thing that bugs me, is the video is too small, its pushed up by the peoples faces. Making screen sharing less effective.
There is a simple fix. Zoom out.
CTRL + “-” or on osx CMD + “-” till you get the size you want.
Works surprisingly well and no extra plugins or config changes needed. There are other plugins/tools if you want to go full screen etc, but this was enough for us.