vi defaults to vim on some of my machines, to nvi on others. I like to have access to both.
vim pros: syntax highlighting is often nice (though when I really care about highlighting, I usually use Emacs), vim's :help is very nice, vim is usually installed
nvi pros: the small TCB I prefer when I'm root (`find /usr/share/vim -name \*.vim | wc -l` just gave me 1103 results, including hundreds of scripts that might be run without me explicitly asking for them), no splash screen, avoids the autoindenting that is often irritating, bound to vi on FreeBSD
vim pros: syntax highlighting is often nice (though when I really care about highlighting, I usually use Emacs), vim's :help is very nice, vim is usually installed
nvi pros: the small TCB I prefer when I'm root (`find /usr/share/vim -name \*.vim | wc -l` just gave me 1103 results, including hundreds of scripts that might be run without me explicitly asking for them), no splash screen, avoids the autoindenting that is often irritating, bound to vi on FreeBSD
I can't say nvi vs. vim efficiency has been an issue for me, but it has been for some people ... http://www.galexander.org/vim_sucks.html