Anyone sank their teeth into this?  I'm looking for the gotcha in it.  Guessing it's probably after the 2 years is up.

Basically, if we go with the payment plan, at the end of 2 years, we actually pay $500+ less for the phones and data in comparison to buying them upfront and signing a 2 year agreement - at the end of the 2 years.  They subsidize the monthly network/access cost if you go with the payment plan vs the 2 year, they do not. 

What am I missing... I'm not a fan of "payment plans", especially for phones!