Houdayer knows what he's talking about, but he's the only one: his English is unintelligible, embarrassingly so in office hours. If you listen really closely to everything he says, you can pick it up, but in the process you don't pick up the actual mathematical concepts being discussed. It's really easy to zone out in lecture because you don't hear words, only some sort of babbling. He seems concerned about student learning but he doesn't appear to be a teacher by trade.