The main one is price and there is no remote. You just go into each app from your phone and cast it to the stick
They pretty much all work this way now, using the same interface as chromecast. You can even cast to an Xbox one
I would say that is a disadvantage anyway. I have a bunch of chromecasts sitting in a pile because I decided that the fire TV stick's remote is way more convenient. Also Netflix doesn't auto play the next episode of TV shows when you cast which is annoying