One of the least magical Narnia books, for my money. Puddleglum is a delight, but Jill and Eustace aren’t the best of the protagonists, particularly in their continued selfishness and quarrelsomeness. And Rillian never really gets over his terrible first impression, for all that you know he’s enchanted. And the antagonist, well. She’s more of the same type as Jadis, if more the seductress type. Actually, that point is what makes her less pleasant — her power is in seduction and sensuality, and there’s a kind of Christian horror of that which definitely hasn’t aged well, if it ever worked.
I do wish we’d had more of the gnomes and their land of Bism, though! That bit of magic and adventure might have been enough to elevate the book, if it had actually been followed through.