The mouth is big enough to drop ice cubes into, but not so big (like, say, Nalgene bottles) that a slight bump in the road and it's all over your new Abercrombie shirt. And at 17 ounces, it's big enough to last you a long hike or a Quentin Tarantino movie.
It's a water bottle, so it's not like it's changing the worl—oh, wait, it sort of is changing the world. Part of S'well's profits are channeled back to charities helping provide clean drinking water across the globe.
Verdict? Pour it up, pour it up.
Ryan Hatch is the deputy editor for Supercompressor. That last "pour it up" line is a reference to a 2012 Rihanna song that he heard for the first time last week. Ryan is a poseur and shouldn't be allowed in public; you'll see why on Twitter @RyanHatch.