It looks to me like another way of doctoring numbers so it attracts customers to buy a new phone and spread out the cost in a slightly different manner compared to the "subsidized" traditional 2-year contract (i.e. 2-year loan for the phone).
I've been away from Verizon for 6 years now, but I assume this is somewhat similar to AT&T's Next program, up to a few minor differences. The NYTimes just had an article on their front page about this yesterday (entitled "the $650 iPhone is fantasy, if not fiction" or something).
At the end of the day, people are buying a $650+ phone and just paying for it in a different fashion. 24 payments with an option to leave early (and pay up to the 12th installment) still comes with the responsibility of paying full price for the phone, or half if you leave early. In the "leave early" scenario, it seems to me like you're just leasing the phone and come out worse off at the end. It's a way to feed the "gotta have the newest" habit of the masses.
I still think it's best to buy the phone you want and go with a primo prepaid carrier like Cricket and save money in the long run. Even better, buy a used phone or keep your old one and do this (that is, if you're a smartphone power user. The MMM community has been great about Ting and Republic).