Following the initial recall of the Galaxy Note 7, Samsung issued refunds or replacement devices to consumers, along with a $25 credit. However, the new phones also had problems and caused incidences like a fire on a Southwest Airlines flight. The company has now killed the phone altogether, and advised buyers to shut it off immediately.
Samsung is trying to keep users from straying to other brands, while also trying to stop further financial bleeding from the debacle. In a post, it said that the incentives are to compensate customers for the "big inconvenience" of exchanging the device. That's an understatement, because customers have been forced to handle devices with gloves and return them in a fireproof box. Then, they must wait a considerable period for the replacements, which can only be shipped by ground.
The best option might be to avoid the exchange and get a full refund. Buyers likely paid full price for the Galaxy Note 7, which was just released. The Galaxy S7 and S7 Edge, on the other hand, have been out for six months, and can be found at a considerable discount. For many users, the difference likely amounts to more than the $100 exchange incentive.