I've heard others describe the difference as a UI issue and I can't disagree more. It takes an engineer to realize, but the dynamic real-time updating of Google

I've heard others describe the difference as a UI issue and I can't disagree more. It takes an engineer to realize, but the dynamic real-time updating of Google+ is /not/ a UI issue. You can't just sprinkle some front-end magic on a system to make it work this way. It takes major backend work to allow that to happen. Minor point, but the photo quality of Picasa is truly making the experience for me. Facebook's photos are low-quality and built to scale massively, while Picasa has been built as a Flickr competitor. The quality difference and design tradeoffs really show. I'm a photography nerd though, so maybe this does not matter to others as much. Also, as many have said I think the major hook for Google+ is that notifications are integrated in every Google property.