I already played the game twice - its absolutely fantastic! The story, the little background details, the girls look of course, Jimmys character, and the animations.
But the greatest surprise for me is that RenPy is mostly made for (animated and choice-based) stories but not for exploring or any realtime mini-games. That seems really rare if not unique too me - it's amazing :) Must be as hard as creating Star Wars movie out of a batch file (but far better graphic :D).
I only saw one other game which level of exploring mode can be compared with HHG and thats "Elevator game with Catgirls".