It's YA fantasy - the meta-aspects and the sheer nostalgia make it somewhat more relevant for adults, but I don't see you getting too much out of it.

It's probably an unfair prejudice, but German literature as a whole always seems to heavy and dull to me - which is why most of the German books I've read in the past year or two were either YA, light reading (Caroline Roche - just got her new novel) or crime novels (mostly Stieg Larsson, which obviously was translated from Swedish anyhow). I intend to get around to Steppenwolf sometime soon, after your review, but there are few other classic novels that seem to appeal to me much. Maybe I should read poetry instead, or Brecht's plays... hm, now there's an idea.