Yes. All things being equal, they are locking you in for an extra 6 months post the typical iPhone cycle.The only catch is that it is bill credits. So in 15 months you will still owe 50% of the initial cost and they will still owe you 50% of the credits.
If you trade in a year you lose the credits. This keeps you locked into ATT for 2 years or get a penalty. A contract if you will.
But if you trade every 2 years or more and don’t plan on leaving ATT, it’s a great deal