And the biggest feature of 7.1 is that within a few weeks 4 out of 5 iOS users will be running 7.1. http://arstechnica.com/apple/2014/01/apple-80-percent-of-act...
Given that Apple still sells an 16GB iPhone (for some baffling reason) I wonder what percentage of users will not have the necessary 4GB of unused space. Anecdotally, Several of my officemates have had this issue.
My kids though had about 50Mb free each.