Eh, depends on your preference of fashion. His style tailors more to the high-fashion of the fashion market; stuff you'll see in European runways and most likely not things you'll see everyday on the street. A lot of them might come across as really silly but there's always something interesting beneath all those outlandish outfits and designs. He's got an eye for cohesiveness and pattern themes which translates really well to designs in both demons and humans in a setting that's (very literally) seen the end of the world.
I've posted this before but I've always found this particular blog post a pretty interesting read in regards to Kaneko's style of fashion design.
Not gonna lie though, he does have a few duds.
That's a fun article, and it kind of puts an interesting spin on all his demon designs. I never really viewed them from the high fashion standpoint.