"What really struck me was the amount of inconsistencies I found: coding style, duplicate subsystems, prices being calculated with tax then re-calculated to remove tax, character set conversions that no one was able to explain—even legacy controllers, which look like they were designed to execute a single action, had been subverted into incongruence in order to handle multiple actions. It really looked its age: layer over layer of changes made by a thousand hands shuffling things around over the course of a decade, without really understanding why things worked that way nor what the original intent was. Some subsystems had even been replaced by new ones without anyone being able to explain why or how they were supposed to work. Madness!"
He is talking about PS 1.6x - the code TB is based on. I assume that now, TB is very different from that description.