One of my good friends is a Maher fan. I don't get it, personally. The main thing that irritates me about Maher is that he tries to come across as some libertarian, open minded pundit. He doesn't necessarily say he is a libertarian (that would, obviously, be an outright lie), but he tries to imply it.
If I had to categorize Maher, he would be a card-carrying ACLU liberal; that is, he separates himself very slightly from modern liberals in that he is somewhat politically incorrect to the fine point that his comments can be socially insensitive all around, thus earning an aggressive "1st amendment first" mentality as defended by the ACLU.