I pay $65 a month on with my 6+. Worth every penny being able to use LTE everywhere I go and not rely on wifi. I need my dat to follow me.
The problem I hear was some folks get a subsidized Iphone... they pay $200 for it instead of $650. However, the carriers would jack up the rate for data + celluar such that you pay $500 to $1200 more over a 2-year contract than if you just bought the phone outright.