I guess the biggest problem with this game is the minigames and quests are hard as hell, confusing, or downright impossible, for very little pay off. Catching the snitch is a pain, guessing at what underpants delphine is wearing is a lot of trial and error if you don't search around in this thread for the answer or the superior walk through, etc.
For example, just to see hermione take her shirt off, but still hide her tits, you have to get an S plus on the hard mode cat puzzle, which is only possible by pure luck, dozens if not hundreds of reloads.
By the time you'll actually be able to fuck one of these girls you'll have to solve advanced calculus problems for every thrust.
Which is a shame because the art and design of this game stands above all the rest, thats what keeps me interested.