The show treads some well-worn tracks in terms of its themes (friendship, selflessness, love & loss) and a few cliche anime plot devices (Young Adults fighting each other with magical powers) but the setting & story are creative and intriguing - a small community, some of whom are born with mysterious psychokinetic abilities, are sailing aimlessly aboard a drifting island which they call the Mud Whale; after decades of isolation they suddenly discover they're not alone in the world, and the outsiders may know the tragic secret behind their magic...
This story, combined with the beautiful art & animation style - the vistas are almost like oil paintings while the magical elements are added in stunning CGI - makes the Mud Whale feel like its own unique world. The main characters are likable and they develop well as the show progresses - in some unexpected ways too, which are equally heartwarming and heartbreaking.
Overall, its one of the best anime which Netflix has involved itself in (not that there's a lot of competition) and definitely worth a binge if you want an anime with less bombastic fighting & fanservice, and more understated emotion & quiet beauty.