I wanted to like this show. Hand to God, really. It was probably one of the most visually unique programs I'd found in recent memory, and its commitment to the visual theme of a circus reminded me of Soul Eater's gothic design motifs in a refreshingly good way.
But having finished its (insofar) only season, I feel exhausted, and yet, content-wise, I feel grossly underfed.
The main problem is Karneval wants so badly to be a big, interesting anime with big mysterious overarching serial plot threads. It wants to do the FMA:B-esque slow, controlled, gradual reveal of information. All of its arcs (save for the one that
finds Gareki revisiting his childhood home—probably not coincidentally, the show's high watermark by a long shot), aim to pique the reader's curiosity about the mythos and the big picture first and foremost, but lose focus on being satisfying in the moment.
So, throughout its run, Karneval withholds exposition and lore from the viewer, thinking it's being tantalizing, but it crosses the line well into confounding.
So when it comes time to reap the benefits of all these seeds it had sown throughout the course of series—at the cost of its episode-to-episode (or even arc-to-arc) quality and general enjoyability—it fumbles. It simply can't cover them all. It shucks and weaves throughout a giant, chaotic battle climax to touch base on them, and satisfyingly concludes none of them. (Probably the most egregious offender is Nai's quest to find his old friend Karoku—an incredibly enigmatic character, frequently teased by the narrative, whose role and character are both woefully underexplained, even by the show's end.)
I haven't read the manga, but what this smacks of is a poor adaptation, biting off more source-material plotlines than the anime had room to chew. With its lack of conclusions, and so many balls still in the air, characters introduced to hardly ever be used, not to mention its too-optimistic sequel-begging final scenes, I feel like I just finished watching the pilot to a show, not its entire first year (and possibly its entire run).
And sure, the visuals are amazing. The characters are fun to watch interact with each other, even if they are a little short on development (although, with a cast of 24 characters for a 13-episode series, it was inevitable some of them would have wound up a little undercooked—again: overambitious source material selection). But all in all, I'd say unless there's something about the premise or the art that really speaks to you, getting invested in Karneval is primarily a discouraging venture.