This game lovingly recreates Hogwarts, with dozens or possibly hundreds of rooms, down to sub-corridors.
In this huge world, everything Hogwarts has in the holidays is implemented: Hagrid's hut, the owlery, Dumbledore's office, all of the classrooms, the dungeon, Filch's office, Hogsmeade, etc.
In this vast and sometimes overwhelming maze (for which lavishly illustrated maps are available), there is a mystery afoot. After a longish introduction where you explore and look for your wand, you discover a missing student and a professor with a cloud over his head.
This works, but its exceptionally long, and this makes the usual adventuring process diluted. The lack of regular gameplay can be ameliorated by the wonder of exploring a Potter world, but this will vary a lot from player to player.
I played for 2 hours and decompiled to read the ending. It seems exciting in parts, but the great spread-out-ness and the difficulty in finding clues made me bounce off emotionally.