Well, the amount of adequately twisted book lore, all the known characters we've had so far, Hogwarts, Quidditch, bits like Weasley brothers' magic shop or even the freaking Marauders' Map, the funny take at the headmaster's activities when he's in the office all day or what Snape does in his dungeons, to name just a few things, for me that's a lot of HP in it, nobody says it's a HP game in a serious category, but for a parody it qualifies pretty much in my opinion, one can only look at the lewd stuff, but there's much more than that here.
Personally I found the humour and a twisted take on book characters/lore the most appealing, although the irony is, as you pointed out, the game is focused on other things, but alas, that doesn't stop one from enjoying the whole package, well, I'd play it even if, for example, there only were conversations between Snape and Genie, they're just great, the feeling that this Snape personality is so books/movies like, makes it irresistably enjoyable, same with the girls' characters, they're spot on book/movie characters. I'm impressed in how much work was put into that lore accuracy, and how that works, Hermione can be annoying, Luna is loony and so on, it all makes the interactions rewarding.
Of course I agree that it'd take even more time than it's taking now, first of all it should be a priority to bring more content to the existing characters, sure, Susan, Astoria, Tonks, there's much void there. But I like giving a good project bigger expectations/wishes, one should never be content enough, something can always be even better. I'll add what I meant about the main plot, well, to be precise, something like what we've had already is on my mind, e.g. another Cho's quidditch match or the Yule Ball, some events that happen when a certain amount of time passes, I had most fun when after a few or more days Snape or somebody would barge in and say that *something* will be happening. besides our usual daily "tutoring".