I have tried it out, and it seems to be a much less efficient way of navigating the filesystem than any average file manager. I guess one reason for this is the ability and requirement to do spatial navigation rather than structural, giving the user more freedom than needed.

But another thing catched my eye there. The representation reveals information that is less visible in average file managers. At a glance one can see whether a directory contains many files; file manager usually show the first n files regardless of whether there are 3 more or 300 more in a directory. One also gets a good impression of the nature e.g. of /etc/rc.d/rc?.d due to how links are represented.

So my conclusion is that this interface is not an efficient tool in its entirety, but it gives a couple of hints about what information is lost in traditional file managers.