How does it compare to Plex? Seems very similar.
Besides the usability and ease of use, it's pretty much the same concept :)
Plex cannot solve these issues easily, because of it's technical design, the add-ons system / concept itself and the server architecture that is so important for their users
Think of Stremio as a possible Plex for the masses.
So my quick review: It's like Plex with popcorn time built in.