I put CM on the two Xiaomi phones I own, but other people are quite happy with MIUI. It's seems to be fairly polished and is updated regularly. Not sure how it can be described as useless.
I don't get the poster above either, the success of MIUI is what propelled Xiaomi into their hardware business after all. There was (and probably still is) a decent following in the west maintaining many community ports of MIUI.