The Not-So-Good
Gear is handwaved. There are no tables of weapons. Armour has no game effect. The system is totally focused on fiction, and is not simulationist. This may not be to your taste.
Combat is purely fictional. There are no stats for monsters or enemies. They do not have hit points. They don't even really need stats. A combat scene is simply a Challenge scene, where you roll skill checks to deplete the dice opposing you. This is not everyone's cup of tea.
Creating your pool felt kinda complex at the start. You assemble different kinds of dice for Stats, Distinctions and Values. You roll other dice for Assets (like special gear). You can spend Plot Points to boost some types of dice to a bigger size, and this sometimes activates special abilities which give extra boosts. You can voluntarily take a smaller dice sometimes, which replenishes Plot Points. If the enemy is injured, this counts as bonus dice for you. This process felt quite involved, and certainly not as simple as "roll 1d20 + skill". The explanation on page 72 is clear as mud to me (see screenshot below).
Values are not always easy to apply. The Values are Devotion, Glory, Justice, Liberty, Mastery, Truth. In some situations, it is easy to pick an applicable Value for your character which applies to the scene. For example, a character could use Glory when they are flamboyantly doing swordplay. But what about a perception check? What Value is applicable there?
Setting difficulties. As presented in the cartoon series, the setting seems too childish and two dimensional. The main factions we see are humans versus elves. Crime or poverty is never depicted, in either the elf or human societies. Adventurers don't really seem to be a thing, nor exploring ancient ruins. There is no core conceit for the game, unlike, for example Shadowrun where the players know they are going to play criminal runners who do jobs against corporations. In Tales of Xadia, your session zero needs to define this for your group, because the setting does not really support D&D style adventuring parties. You need to be human royal guards, or a crack squad of elf assassins. You need a clear goal and a reason for your group to exist and stick together. And coming up with a conceit that allows a party of mixed elf and human and dragon players could be quite tricky. The book does not really help here, and so I have my doubts over how successfully the TV show setting can be translated into an RPG setting.
Too many stress trackers. Your character does not have hit points, you have 6 different types of Stress that increase. Afraid, Angry, Anxious, Corrupted, Exhausted or Injured. When you fail a skill check, then one of these will probably increase and become a penalty dice. It felt quite a lot to track, and the Roll20 character sheet we used forgot to include this part of the game.
