I dropped this show after 10 episodes or so, but I wanted to like it.
Main character looks cool and so do other characters and their pets.
Fighting scenes are well done.
The story is surprisingly for the genre, very unpredictable. Supposedly dead characters pop up again episodes later and people get captured or visit a different dimension in the middle of a fight or crisis. You never know what's going to happen.
The main character looks cool but has a bland personality of a turnip-with-an-attitude. This is the guy that's supposedly there to be liked and drive the story forward, yet all he seemed to do was annoy me with his I'm-too-cool-and-moody-and-brash-and-everyone-loves-me-for-it. He's like Naruto but worse. He is not endearing in any way.
There was one part where the main character was supposed to undergo a trial. One of those trials where it’s not really about your physical skills but your mental or spiritual aptitude. Well, the main character just wins by being stubborn and the old dude in charge of the trials just congratulated him for it. Like if he had been wise or honest or something worth it of praises, but he just kept on being arrogant and brash. Great! The show is trying to shoehorn his character into my liking but showing other people approve of his personality. Well, I still think he’s a punk! And this happens several times. Instead of getting slapped in the back of his head, everybody acts like “he’s just that way and he seems to be on the wrong but let’s support him anyway.”
The fights are similar to Pokemon, or at least that’s how they immediately feel like. Everybody’s guardians are giant pets and in every single fight they get called or summoned to do all the fighting. After a while, I could not take the whole concept seriously.
Characters act quite unpredictably too. For example, one of the characters gets a moody break and decides to go on their own back to a place (world/dimension/whatever) where they very recently got captured, held down and nearly killed in a ritualistic fashion just because that’s where part of their family was from! Yeah, that's reasonable. Because nobody can relate to me, I’m just going to go to the place where I will most likely get re-captured and disemboweled.
If you don't mind giant pets doing the heavy physical work for their masters, (the bulk of all the action scenes in this anime) and can withstand variable degrees of boring or annoying main characters, then I guess you can enjoy this well-animated series.
For me, it didn't work though I wanted it too. Luckily, there's more similar stuff out there.