Many people probably didn't notice that Microsoft Office at that time used custom controls and was a little off from this design.

The design was very nice, but a bit over complicated. Things looked like a control panel, which maybe makes us feel like pilots, but intimidates most users. The open dialog is a good example. Drop down elements, lists, directory list, label for selected directory. Later iterations fixed this and nowadays apps try to avoid selecting files altogether if possible. Overall, design has improved a lot since then, maybe except for the touch additions.