Sometimes he's a good asshole, but lately he's been on his anti-religion zealotry binge and he sounds every bit as bigoted, stupid and vile as the fundamentalists he is ranting against. There are some atheists who are every bit as fundamentalist and xenophobic as the various fundamentalist religious groups around the world. They hate religion and religious people like Fred Phelps hates gays: irrationally and with heavy doses of scorn and vitriol.
I saw a bit of the segment with Ben Affleck and I liked that Ben stood his ground against the fundamentalists at the head of the table, but Reza Aslan is right: you can't argue to convince Bill Maher: his viewpoint is not rational. It is emotional, and he cannot be dissuaded.
Incidentally: the whole of that linked interview is really good.