It's funny how everyone shits on his code yet there's no other renpy game on this site with this level of depth of mechanics.
You know I've always been on the side of "His code isn't bad for someone who's never formally learned how to program and he's improving his code." But some of the complaints are valid. Using an event registry system like in TNH is a better way to go. Having object and/or class inheritance is a better way to go too. But, again, these are not things you would know about unless you've taken 1 or 2 classes in programming.
Plus, python is one of the slower languages, even for interpreted languages. I'm convinced that if renpy was written in another language, even PHP, it'd run faster. It's not even the easiest language to pick up. It's just what's around because. If there was a more common/well known VN game engine, I'm pretty sure there'd be, like, 20~30% less complaints.