Then the narrative form abruptly lurches sideways about two-thirds of the way through, and we realise that this is not quite the book we thought we were reading - and in fairness it is a move that has been well enough signalled. This leaves Gaarder with minor difficulties in resolving the plot, but that doesn't matter all that much.
On the substance: I have (whisper it softly) never been terribly excited about philosophy, but Gaarder does unpack the relationship between Hegel and Kant better than I have seen elsewhere, and also guided me through the relationship between philosophy and literature (at least of the last three centuries or so). So I learned something, which was partly the point.