This manga has everything. It has comedy, with really funny facial expressions, too. It has a large cast of characters you care about, who are complex and dynamic. It has plenty of action with an engaging strategic narrative like you'd expect of a good shounen. And it has powerful existential themes, which aren't just abstract, they're driven by real events and experiences.
The storyline is creative. New developments occur pretty frequently, but rarely with spontaneity, and they're never isolated experiences. It surprises me what the author does with the characters. The characters aren't just dynamic, they're incredibly dynamic, unpredictably so. Their emotional relationships, and the feelings of comradery, kindness, sadness, passion, and appreciation that pass between them, form the basis of the serious side of this story.
Although you often see characters running around zanily, the action itself is completely realistic. As it pertains to humans, at least (demons have more endurance and speed / physics-defiance). I thought for sure there would be a lot of unserious moments, where for comic or dramatic effect the rules would bent, but no. There are certainly what could be (meanly) described as deus as machina--unavoidable when the manga's pacing is so fast--but for someone who had never read a story before and knew to look for such things, they would experience zero breaks in their sense of realism, and I believe that's really saying something.
Volumes 25-30 of the manga were released after the 150-episode anime adaptation ended (I don't know what the anime covered, though), so I'm glad that a group (or groups, if Anime-Destiny were to also start releasing consistenly) is willing to take on this unique series, so I can see its to the author's intended conclusion, which I hope will be in the distant future.
Definitely worth checking out. The first few chapters are probably enough to give you an adequate sense of what the story's potential is. Not a masterpiece, but certainly a work of art, and one that's totally enjoyable.