Those are shared/team offices, not open offices. And I agree: it has been the most effective configuration I've worked in. I used to work in an environment with 4-5 people per (large) office. It worked out really well, and we'd reconfigure the seating arrangement as needed. Where I'm at now the entire building only has three private offices, the rest are completely open. Those type of spontaneous, collaborative discussions are helpful, but tend to piss off the other ~10 people within earshot more often than not.