Hmm, the idea of "grading" how well the player has executed the task is cute, but the execution is... questionable. E.g. two early tasks:
"see Ariel at her place of work", the entire difference between C and A+ is, for the latter you need to visit her early enough to make her spill coffee on herself and then perv on her while she's changing. Which... doesn't exactly have anything to do with finesse of doing your work as a thief.
"go with Bella to the tattoo parlour" is even worse in this regard, because it decks you a point if you lie about your connection with Bella to the guy you're questioning, instead of just blabbing like an idiot she is your "roommate". It also decks you another point if you let Bella play her female wiles on the guy to extract the information from him, instead of doing it yourself. And yet another point if you're "charming" instead of "composed" when questioned if watching another girl's pussy bothers you. I mean, are these gradings of how well you work as a thief, play roles and execute your tasks, or whether you avoid pissing off your bitch of a sister? Because the tutorial might use some rewording, if that's the case.