I'm probably late to the party, but I've just loaded the Raring beta and was _very_ disappointed to find that tree view is gone in Nautilus. This means that the file manager can no longer display an overview of the file hierarchy. It also means that Nautilus is not much use for moving or copying files to multiple disparate folders which don't share a common parent (for example when sorting out and categorising a bunch of files) or tidying up a file system hierarchy. For me these are common use cases. I realise that not everyone uses Tree view, but when you have 1000's of folders, many levels deep, and 10,000's of files I think it's hard to manage the file system without it.
I now understand that this is an upstream Gnome decision (though one I can't begin to comprehend - their reasons make no sense to me). Whilst it's possible to load other file managers such as Nemo they won't integrate as well into the Unity interface as the native one. Does anyone know if the Ubuntu devs are considering how to address this? I regard it as a vary significant regression in functionality and I hope that they will do something about it.