As a long-time Dolphin user, I can't help but disagree. When I go back to Windows' Explorer or Mac's Finder, the lacking features irritate me. Dolphin's information density is just right, its URL bar has just the right blend of point-and-click and tab-completion to it, its drag-and-drop gives you the choice between copy and move, you can right-click compress and decompress archives and its contextual actions are exhaustive (open terminal here, install font, …), and it plays well with remote directories (ftp, samba).

The only time it disappointed me was when I wanted to open an FTPES directory, but the bar is high.