One problem for a vim user like me is emac's terrible first use experience. The delete key doesn't delete, it opens up help [1] and quitting is very difficult [2]. Also what people don't know at first start is which key is their meta key. A key that is super important in emacs. That it gets this first basic experience so terribly terribly wrong turns a lot of people off within a few critical settings of having run the thing.

[1] http://www.gnu.org/software/emacs/manual/html_node/emacs/DEL...

[2] http://www.ugrad.cs.ubc.ca/~cs219/CourseNotes/Unix/emacs-sta...