It has a simple and easy-to-use navigation tool bar. Its options are, in my opinion, easy to access, hence, they are not buried into a lot of menus, like Konqueror. But don't understand badly, Konqueror is the best file manager that I have used in my life, but it's a bit "swollen", so, it's a navigator, a file manager and more (as described in its website), I think it's really in time to change this, Konqueror is a navigator and Dolphin a file manager, each one in your side.
I really like the easily way to use Dolphin, simple options but enough, some of them are quite interesting indeed like disk usage in right bottom corner, I like it.
So, if you are like me, a new Dolphin user, and you are interested to use it as a default file manager in your KDE, just right-click on any folder and select "properties", after that click on "Edit File Type" button, near to "Type" information. In that window, add dolphin as the first application to open folders, just that, now dolphin will be your default KDE file manager, so, any folder will be opened using it. Of course, don't forget to install dolphin before.
So, that's it, enjoy Dolphin!