Our hangout usage is mostly for meetings, which are just check-ins and planning meetings. Typically during the course of a meeting several people will briefly screenshare what they're working on, and a typical meeting involves multiple time-zones and states (although we're all US-based).
Sometimes pairing is done using hangouts, which isn't the best solution, but also isn't overly inhibiting. We are a small company, but > 15 developers.
I've never wanted to drive the coworker's screen, however I could see how that could be useful in many cases.
I'm not particularly thrilled with hangouts, in the same way I'm not particularly thrilled with, say, ssh--but it has always gotten the job done and allowed me to share my screen with others painlessly.