While the vim keybindings and modes in the editor are ok, it really lacks the keyboard-driven window and panel control you have with vim. Basically, the UI still needs to be driven with a mouse, which totally breaks my workflow. As another commenter put it, vim-mode is a bolt-on, rather than an integral part of the editor.
And while vim-mode is impressive, I don't think it's really quite enough, unfortunately. Because the problem is that vim-mode isn't core to Atom's design philosophy, it's a bolt-on that tries to import a different philosophy to Atom. Other extensions (and native commands) don't expect to be in vim-mode and don't natively work in a way that extends vim-mode.
I like the atom effort, and I think it may come a long way. But it also still has a long way to go until it is as mature as emacs.
Another good thing of emacs that I only recently started to appreciate is LISP --the grandpapa of all dynamic languages-- that is used for both emacs scripting and config-file format (they are kind of the same). JavaScript, how ubiquitous it may be, will never be as "impartial" and "timeless" as LISP.