At first, Passing Familiarity welcomes you in, by presenting you with a sympathetic protagonist. As the game progresses, you find out that is merely a parlor trick, as the protagonist is actually altogether unsympathetic; the welcome is only for the purpose of being stung by barbs.
To be specific, the protagonist begins her story as someone with a faulty memory (yes it's a cliche`, but I don't hold that against the author). Naturally you want to help her recover her memory. Only as you discover more clues to who she is, you really don't want to. Her self-centered sense of entitlement, her anti-Christian bias, and the decided slant of the game towards witchcraft (and all its pagan/Satanic overtones) as opposed to alchemy, magic, or other terms, seals the deal.
You could argue that the characterization of Christianity in the game is merely a characterization of its corruption, and not of its true essence; that's the line that many opponents fall back on when questioned. Of course, the lack of a positive counterpoint and their vehemence reveals that they cannot conceive of any "true essence". The author has every right to make a game with that as a primary component, but a warning would have been nice.
The descriptions are concise with occasional embellishments; they serve well to make the rooms memorable in a few short sentences. There are a multiplicity of objects which would make figuring out what is supposed to do what probably a chore. I can't comment on the other aspects of the game, because I found it simply not worth playing once I knew the protagonist.
This is a warning sign more than an exhaustive review.