The reason to pick up vim is ubiquity, not efficiency. And you REALLY don't need to know much. Maybe half of what's in the vimtutor tutorial is enough. Personally, I'd also suggest at least learning how to do search/search & replace with regex which is easy too (and bonus, has high affinity with sed.)

That seems like the most any modern developer/*nix user should need to concern themselves with vim and wholly for the reason I mention above: it's the most likely text editor to be there on unix-like systems.