Reasons to Use Vim over Vi

This page Difference Between VIM and vi goes over some of the advantages of vim over vi. (Note: the page disappeared, so now we’re pointing at the Internet Archive’s March 2011 cached version.) 
 To list some useful features: Multi-level History 
 
 Undo – n u ( n is the number of levels) 	 Redo – n ctrl-r 
 
 Windowing 
 
 horiz split – :new file 
 	 vert split – :vs file 
 	 next window – ctrl-w ctrl-w 	 prev window – ctrl-w ctrl-p 
 
 Visual mode 
 
 start – v 	 finish and… 	 move – h,j,k,l 	 change – c 	 delete – d 	 yank – y 	 alter case – ~,U,u 
 
 Command Completion – tab 
 Insert Completion 
 
 match dictionary – ctrl-x ctrl-k 	 match from includes – ctrl-x ctrl-i 	 match line – ctrl-x ctrl-l 	 current file 	 next match – ctrl-n 	 prev match – ctrl-p 
 
 Additional info: http://csswizardry.com/2014/06/vim-for-people-who-think-things-like-vim-are-weird-and-hard/