Purchased it yesterday, also learned to sideload, my impressions-
First the good, like the interface of the unit better then the Roku, a little slower then my Roku 4, but i like the look of it better.
Picture Quality at 1080P for some reason is better then the Rokus, went back and fourth using my receiver to switch inputs watching the same programs (used Vudu, Netflix and Food Network) on both boxes and the picture was sharper and better colors on the MiBox, do not know why, have not tried 4K yet, will later.
The bad, not enough TV Everywhere apps, a lot less then the Roku, I have written before that I like and use these apps on the Rokus since I refuse to put cable boxes in every room in my house due to costs and they would get seldom use ( like my kids rooms), android TV needs more, I did sideload a few of the tablet/phone apps and for some reason the picture is sideways on them, I do not have hope that Android TV will have more since they always seem to give up on the format and then start over and try again.
Sound, only getting PCM, no matter what option I hit-HDMI, Bitstream, Auto it only comes out as PCM.
No Ethernet port, should have checked that before I bought it.