The 'snap' sound Snarly mentioned is, I think, from the heavy rotation (super spin) and the clean way the ball goes through the hoop (high arc helps this).
The guy is just a pure shooter, and as he said himself after the game, his tall frame makes the shot even easier for him. He has like perfect form.
What's great about Miller is that he's tall (probably a legitimate 6 foot 8 or close) and he seems to have pretty long arms as well. This helps him on defense (like that block he had against someone before he got hurt. I cant remember who it was) and it also helps him with rebounding. He's deceptively long.
What I remember about Miller when he was in Miami is that he would drill clutch threes and also get key rebounds and stops when the team had to have them. He's not getting any younger, but for now he's a great asset and if he's in shape enough to start, then let him start.
He also has a very high basketball iq and he knows how to play with LeBron. And, he seems to be a guy all his teammates love and get along with.
The best thing about starting Miller is that he opens up space for LeBron and Kyrie to drive. He has to be guarded on the perimeter.
If I were Blatt, I would have the
LeBron/Love/Miller trio on the court a lot together. Love needs LeBron to get him the ball, and LeBron needs Miller/Jones to help him get better and bigger driving lanes.