Largely, with the unintended parachute nerf and the size of the map combined, mid game is EXTREMELY boring.
To combat this my squad generally looks for drops to fight around, but drops also have an innate problem, the plane is hard to spot. This could be from an overall higher elevation from "sea level", the large mountains that obscure long lines of sight, or maybe the plane is literally lower in the sky. It would be better if the plane was higher, or the mountains were made shorter. There are areas where you can hear the plane but never see it due to terrain being so damn big.
Which leads to my next point, the map, due to lack of water around the edges, is just so damn BIG. This map could easily use another 50 players to the start to make it more fun mid game, or just shrink it down. Honestly, Miramar's biggest flaw is how large the map is and how long the fights become. Every fight is a sniper battle late game, unless you get the rare city ending.
Speaking of late game, in Erangel you get prone in field battles, city fights, sniper fights, hill fights, etc. It's pretty varied towards the end. But the monotony of Miramar's features ensures the same overall ending: On a hill where 1 team already has the ridge and you lose because there's no grass, no cover, and you have to cross a barren rock plain under sniper fire.
My friends and I like the better frame rates in Miramar, and we like the varied buildings, but the mid to late-game play is so mind boggling boring/repetitive/generic that we prefer to queue Erangel (bar dropping in Yas which has horrible FPS issues).