The popup menu is the new location for the hidden menu that you used to get by command-clicking in the title bar of a window. Next to the popup menu is the most radical change. Browsing in place is intended to reduce window clutter and can potentially make the interface less confusing. But it remains to be seen whether this will be offset by the disadvantages of breaking the desktop metaphor that has served Apple well for more than fifteen years. One of the reasons the current Finder is so efficient for me is that I have many windows open at once and can easily recognize them by their shapes, sizes, locations, and icon arrangements.
Different people have different work styles.
If Apple makes it easy to switch between the new and old Finder looks and behaviors, they can make nearly everyone happy. However, I am concerned that the list view Steve Jobs demonstrated did not have disclosure triangles to expand folder contents. This was one of System 7's best innovations, and Apple would be wise to keep it. Dialog Sheets Open and save dialog boxes now slide out from document window title bars, making it clear which document they pertain to. These dialogs have always been the most difficult part of the OS for new users to intuit.