Not really, it depends on your plan and carrier. On Verizon, any device on a "Device Payment Plan" (formerly Edge) gets a per-line credit which varies by how big your data plan is. For my plan I get a $25 credit per line on a DPP, which I would not get if I simply paid full retail for the phone.
That line credit is the key, since over a 24 month period I'm getting $600 credit just for financing my phone, which I would not get by buying outright. At the end of the 24 months I own the phone just as if I paid up front, but paid $600 less for it. If I choose to upgrade my device before 24 months I can do so by paying off the balance, but I'd lose the $25 per month credit for any remaining months on the payment plan.
So let's say I start a new DPP for a 64GB 6S+ and a year from now I want a 64GB iPhone 7. The 6S+ would cost me $10.42/month ($850/24 - $25) or $125 for the year, then I'd owe the remaining 50% balance of $425 (no per-month credit on the balance), so a year into the contract the net cost to me is $550 to fully own the phone instead of $850. The $300 savings comes from the $25/month credit over the year. I could then sell the 6S+ to mostly offset that $550 cost, heck I might even break even.
So at least in Verizon's case the financing option is a very attractive deal, as long as your data plan is large enough to get the $25/month credit (I think 6GB/month and up, otherwise the credit is $15/month).