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/