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.
If you were worried about non-www links working during downtime/issues, you could setup multiple cheap hosts around the world with nothing more than a rewrite to the www. subdomain (where your main app is hosted). Then add the multiple IPs to your root domain's A records - that way you have no configuration to worry about (the non-www hosts literally just redirect to the same path on a different domain), and you don't have to worry about those redirects going down due to DNS round robin on multiple hosts.
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.