How do bill credits work

[throssel]

I've been wanting to get the new Galaxy S8 or S8 Plus through U.S. Cellular. They have a deal where you can get the S8 Plus for a little under 4 dollars a month with monthly bill credits. How does this work? Will I end up paying the same amount in the end as I will for paying through installments? Where are the hidden costs? Any help would be appreciated