My first reaction was that this is a crock... after all, don't all the big hot internet companies use root domains? But I looked into it, and Facebook, Google, Apple (and Heroku) .coms all redirect to www. Only Twitter rocks the bare root domain.

I rely heavily on root domains in my printed materials (sending people to sproutrobot.com/water and such), but I'm starting to think redirecting users to www--so bookmarks, social media and the like point there and the majority of my users hit www first--is a good idea.