Finished Piranesi, which on the whole I liked, though it somehow felt a little "slight".
My thoughts too, especially the absence of any explanation for the amnesia on which the whole thing depends.
I finished Susan Cooper's The Dark is Rising (book, not sequence). Wonderful magic, imagery, atmosphere, prose, and lovely heartwarming depiction (without schmaltz) of Christmas in a large family in the 70s. (I think this has replaced Dickens as the archetypal Christmas for me).
Where it was slightly unsatisfying is that Will never seems in real danger, doesn't feel like he undergoes real hardship, and has to make very few choices. Part of this is the effect of prophecy, I think. Also, the rules of the magic and the cosmic battle are unclear and seem to change as convenience dictates. These are things that didn't bother me as a child reader, and probably only bother me now because I'm a writer, but the flaw feels a shame in something otherwise so good.
I've recently read the subsequent book, Greenwitch (which didn't have this flaw, or not nearly as much) so I'm skipping to The Grey King.