Shuffly is not a replacement for the YouTube app, they serve different purposes.
Sometimes YouTube can be a little overwhelming, Shuffly's minimal and straightforward design is thought to solve this problem.
If you want to relax without having to worry about what to watch, just pick the "Videos you may like" or the "Trending" option and let Shuffly do the work.
If you want more control over the video playback, you can shuffle by keyword, category or you can choose between all the channels on YouTube: it's super easy to shuffle over the uploaded, liked and favourite videos of all channels.
Shuffly is a third party app. All the content is provided by YouTube services. Therefore Shuffly does not have direct control over the content that may infringe copyrights: https://www.youtube.com/yt/copyright/
Shuffly is an unofficial app. YouTube and the YouTube logo, trademark and trade dress are registered trademarks owned by Google Inc.