It may compete on those three things, but that doesn't mean a competitor that is cheaper and easier (in sign up & use) will win. Brand recognition, reputation, quality of support, switching costs, customer intertia, and probably other factors all matter. I'd rather try to create a new market than displace Square's customers, let alone compete w/ other "cheaper, easier" Square competitors.

Relevant:

http://en.m.wikipedia.org/wiki/Blue_Ocean_Strategy