There's consistency issues with invoking help. For instance doing:

wp help db chec

(or wp help db asdf) in an install (or pathed to an install) will just exit, printing nothing. Whereas:

wp help db chec --path=/nowhere

will come up with the "not a WordPress install" error, which isn't very helpful either, while both

wp help db --path=/nowhere
wp help db check --path=/nowhere

will come up with the help screen, but

wp help asdf --path=/nowhere

won't but prints the "not a WordPres install" message.

Suggestions on typos in commands in help don't appear either, eg

wp help confi
wp help packag
wp help core instal

just say they're not commands.

Another issue is with the auto_check_update() which if forced to trigger by:

wget https://github.com/wp-cli/wp-cli/releases/download/v1.2.0/wp-cli-1.2.0.phar
echo 0 > ~/.wp-cli/cache/wp-cli-update-check
php wp-cli-1.2.0.phar help config

just presents you with the update question and if you say no it just exits.

I'll post a PR.