Think of me as turning into a Aroduc-like hater if you will, but I just cannot stomach Phantom World. It seems... dull. Production values are rather good, but absolutely nothing of interest is going on. And yes, I know that there's some kind of plot thing happening by the end, but it was 10 episodes and nothing of any interest happened, not even in a slice-of-life sense. The monster of the week went downhill: each dumber than the previous one. Most never made any sense to begin with, pure convenience to showcase cast's magic abilities. I didn't see a debacle like that since Tamako Market. On second thought, a glance at the staff lists for the two series explains a lot.

UPDATE: Looks like I'm not the only animeblogger with a similar reaction. Steelbound:

Kyoto Animation was never failed so badly and so thoroughly as they did with Myriad Colors Phantom World.

That said, he faults "horrible, terrible characters" and the animation of fighting scenes. I'm not sure that either is a problem. Looked fine to me!