Showbox is the all you'll ever need app to watch movies and tv shows for free. You can favorite your shows, so that Show Box notifies you when a new episode comes up. This is particularly useful if you are a hardcore fan and want to watch that episode as soon as it becomes available.
The app supports torrent downloads: if you have a slow internet connection and don't want it to stop every 10 seconds while watching this is the way to go. If you do have a good connection, then you can use the streaming feature at 360, 480 or 720p.
Subtitles are supported and, if available at opensubtitles.org, you'll be able to use them, hassle free. You can even stream the contents to your smart tv or Chromecast if you use an app like AllCast or LocalCast.
Show Box is one of those apps that offers very simplified and intuitive menus and buttons, so you do not waste time when watching a movie or show.