The only issue I have with my Mi Box is that it goes unresponsive when it goes to sleep and you wake it up. In the developer options you can disable it going to sleep and also not let applications stay active in the background. Once I set that it seems to be working fine now. Otherwise the Mi Box is a great cheap alternative to the Shield TV. Of course if you can afford it the Shield is better. I own both.

Negatives: The updates are usually slow to come and can introduce a lot of issues. It takes them months to fix them if they are fixed at all.

Positives: The remote is great. I like it a lot better than the Shield TV remote. The Mi Box is cheaper than the Shield with really good hardware and the same UI. All the main apps work great (for me at least).