I think the issues arise partially on how "open" the open floor plan is. If it's just one big room, poorly designed, it seems like a disaster for productivity. If it's a series of pods or areas, with some effort made to provide space between them, and a healthy amount of huddle rooms or conference areas, I think it can work great.

The trick is to provide enough separation and space that people don't feel claustrophobic, and manage a culture that encourages people to take group conversations into a room if they're going to be loud/passionate.