Muggle Studies is a Harry Potter fanfic in IF form, designed -- so far as I can tell -- as an introduction to IF for Harry-Potter-loving fans. To that end, it doesn't do anything terribly shocking from an IF perspective, but introduces a variety of common types of puzzle much in the way that Mrs Pepper's Nasty Secret does. To ease in new players, "Muggle Studies" comes with detailed instructions, a complete hint system, and a sample transcript (rather deliciously, one that riffs brutally on "Twilight"). Parser improvements via Aaron Reed's extensions correct common errors and clean up minor typos for the player, making for a smooth interaction experience.
There are a few odd decisions in the puzzle design. I ran into one guess the verb problem ((Spoiler - click to show)I tried PUT SCARF ON THESTRAL rather than GIVE SCARF TO THESTRAL, and this wasn't recognized as a solution at all; it's also a little strange that the scarf isn't marked as something you can wear, since this seems an obvious thing to experiment with.); several other puzzles are things you can solve by going outside the game before or instead of finding the solutions internally, which might or might not be considered a defect.
"Muggle Studies" also makes use of several outright riddles, something I haven't seen much in recent IF, saving one room in the esoteric "Ted Paladin and The Case of the Abandoned House". Riddles make somewhat tricky IF fare, because they tend to have no connection to an implemented world model and have no hinted feedback on partial failure states; you can't typically solve a riddle puzzle by progressive experimentation. Fortunately the riddles in "Muggle Studies" are confined to one particular puzzle area and are fairly consistent in concept, so the effect is fairer and more accessible than it might be.
These quibbles aside, however, "Muggle Studies" is solidly crafted: I didn't run into any obvious bugs, and it deals cleanly with flashbacks, conversation, and other potentially challenging elements. A nice set of feelies rounds out the package, and I was fortunate to get a copy of the Collector's Edition, in physical form: a handsome black envelope containing the letters and brochures that are also available by PDF.
As story, "Muggle Studies" feels somewhat limited. There's the shell of something here. It's not a story that would stand very well on its own. Too much is unexplained, I think, for a reader who doesn't know the Potterverse to follow, or to have much investment in it, but there's certainly a concept: the protagonist is a non-wizard introduced unexpectedly to the wizarding world, and the story involves the injustices of certain wizard laws, together with the protagonist's relationship with her ex-girlfriend. Questioning the rules of a well-known story -- and thus the preconceptions of the audience that accepts and admires that story -- is one of the more interesting functions of fanfic, from Eliezer Yudkowsky's "Harry Potter and the Methods of Rationality" back to Euripides' Electra.
But "Muggle Studies" doesn't so much richly explore the question of muggle/wizard relations as raise it in a short essay at the end. Because the majority of the puzzle content takes place in an abandoned Hogwarts, there's not much opportunity to interact with the major characters except during framing elements at the beginning, in flashbacks, and at the conclusion. The end does give the player the chance to make significant decisions one way or another, but it doesn't necessarily feel very well connected to the more objects-and-puzzles substance of the midgame. In addition, there's a bit of a player-protagonist disconnect, as the player is likely to know quite a bit more than the protagonist. (Spoiler - click to show)Some of this is because the player may have read Harry Potter before and recognize all the characters; a large part, however, is that the protagonist is shown as failing to notice the clue-by-fours that the narrative is laying on the player. Thus it's clear to the player very early on that both the protagonist's grandmother and her girlfriend were witches, but the protagonist continues not to realize this officially until the end. And because we've spent so little time with the major characters, the player is unlikely to feel as strongly about the protagonist's girlfriend as the story deserves.
The other thing I found myself missing in "Muggle Studies" was an in-depth exploration of Hogwarts as a place and the inhabitants, present or not. The protagonist is a muggle and so cannot do any magic; none of the spells of Harry Potter are available in play. This is probably a safe design decision, since J. K. Rowling's concept of magic is so wildly inconsistent as to be a real bear to implement, and includes such puzzle-breaking powers as the ability to unlock any lock, to fetch any object from a distance, and to produce water from nowhere.
Even with those constraints, though, it would have been nice to see a little more about the personalities and history of the canonical characters. As it is, we get a peek in Lupin's diary and a visit to Snape's classroom, but in neither case are there many hints of the owners' personalities. (Spoiler - click to show)Another missed opportunity was Filch's catalog of detention cards. While it was fun to look through the catalog and find items at random, it would have been more rewarding to be able to look up specific characters and find their records: this kind of content rewards the in-the-know player for demonstrating familiarity with the series, but someone with less background won't even notice it.
All of this is not to say "Muggle Studies" is a poor game. On the contrary, it's well above average in implementation and polish, a substantial debut piece, and the extras show a lot of love and enthusiasm. But I consistently felt that it could have been significantly more impressive if the human content and the puzzle content had been better unified, and Hogwarts given a richer texture. Perhaps the result would have been less of a pattern card of typical IF interaction styles, but it would also have been a better interactive story.