Bought the basic FireStick to use with Plex for streaming media to my TV. It couldn't handle the app very well and glitched/crashed a lot so I returned it and bought the 4K version. Sooooo much better! Runs the app very smoothly and no more crashing.
I have only one real complaint with it. There's no way to have it go to sleep after XX mins of inactivity. It will pretend to sleep, but it doesn't actually turn off it's output so the tv won't timeout and power off. This means the tv gets left on all the time when someone just walks away sheet a show. It's a small thing, but my old Kodi box would properly sleep the HDMI output so the tv would notice and turn off. Saves life in the tv and money on electricity.