What's almost as interesting as what they've built is that they've built this based on Firefox. It's impressive that the UI can be so thoroughly re-imagined with not that much code (not to say it is a trivial project, or to diminish the work put into it; it's very impressive).

I've never thought "I want a panoramic browser", but I never thought I wanted tabs until I had them, and a dozen other large and small now-mandatory features. I'm looking forward to playing with it, to see if it unlocks usage patterns and new efficiency in the way tabs did. Or, perhaps it'll cure some of the negatives of tabs (losing my train of thought, a tendency to always be multitasking poorly, etc.).