Dissolves, like so many other touches, were spot on. He didn't just set it in the 1970's but made it feel like a film from that time. And it works. My daughter saw it at her college and wrote, "Why does no one talk about this film?!" She didn't realize that it was just released.
But what I admired more about this film, besides the impeccable acting and flawless script, was the way Payne hinted at a specific trope and then rug-pulled it away, sometimes dramatically.
For me: film of the year.