I previously had the Nexus player, but after reading about the Mi Box I had to try it out. Setup was easy. Didnt see any speed difference between the Mi box and the Nexus player at first. I downloaded the same apps I had on the nexus player and they all seemed to work fine except one of my games. The game is Modern Combat 4 for Android, and the game looked like the characters were... If you have every been to art school, the way the teach you draw people, with circles, and lines, it was like that but looked like lasers. Sorry, hard to explain.
Also, when casting from my tablet to the Mi box, about every third cast would cause the Mi box to reset, and it would keep reseting every few minutes until I reset it myself, by soft reset or pulling the power plug.
Well I received a small update a few days ago, and I no longer have the casting issues, and the speed over the Nexus player is very noticible now. As far as the game, I havent checked it to see if I have the same problem.
Hoping we have more Mi box users out there.