re: Anyone have any experience with Amazon Fire TV

I did same thing. I am using plex as well. It is awesome. The interface is great and I can actually use my iTunes library off my imac. It also will let you stream stuff remotely to any device that has the app not just the fire tv. It was definitely worth the 5 dollars instead of having to root my firetv and go through all the hackish methods to get that to work. I am starting to realize sometimes it is just worth paying for shite.
One thing about the interface, It actually organizes your movies and puts them as thumbnails with the correct box for movie/tvshow. I am not totally familiar with others as I just used the xbox 360, but plex makes your movies and tv shows as easy to navigate as like netflix or prime does.