I love the concept, and much of the game.
However I have to echo what most other posters are saying, and this is a general comment about the mechanics of gameplay.
The clues are too vague, the locations ambiguous, and the quest log often doesn't present the full clue anyway. Like many of us, I've struggled to locate the correct locations for quests, and find searching the entire castle, grounds and surroundings to be tedious rather than enjoyable.
The maps don't encourage fast travel between locations - they look nice, but there are too many obstacles between places to make it easy to run - also, what's with the wandering animals that get in the way? Hermione blocked by a frog?
When collecting a herb, we get "Herb collected", followed by "This will come in handy for potions". Which is very useful the 1st time, and maybe the 2nd or even the 3rd. By the 48th time I really hate it and am ready to break the computer.
Please take this feedback positively - despite these the game is still enjoyable and interesting to play.