The over-use of the phrase "if it walks like a duck, quacks like a duck..." etc: It irritates me and I don't think it's even a very effective analogy considering that there are plenty of things in this world that really <i>aren't</i> as they appear.
His seemingly zero-tolerance opinions on drinking and gambling: I love a drink and I love to play poker online. I'm responsible about it, though; I think George sometimes (perhaps deliberately) blurs the line between when something is done for fun and in moderation and when something is clearly an addiction, an illness, or starts to become out of control. I'm not an alcoholic or a problem gambler so I wouldn't want my right to enjoy those passtimes removed simply because some people abuse them. I am, however, against super-casinos and the deliberately addictive slot machines - but a civilised game of poker can't be compared to their cynical, subliminal manipulation.
Religion: I'm not a religious person and I don't believe there is an afterlife, so technically I would disagree with him on that, although of course I respect anyone with a faith and believe in the right to be free to practice any religion you choose, so this is a minor point.
His common retort to pro-war callers "are you going to collect your tin hat tomorrow?": I understand the point he is making, and the people he makes it to are often imbecilles, but I don't believe at all that you're only allowed an opinion on something if you are involved directly in it. For instance, if I was slagging off a band that I hated, it would irritate me if someone replied "well, can you play guitar any better?" because that would be completely arbitrary to my opinion of the band.
Finally, I guess I'd have to include <i>general</i> over-use, over-repetition of phrases:
"my great grandmother was the only etc etc... I think she got on the wrong boat..."
"two cheeks of the same backside" (I actually like that one, but he still says it too much)
"a shiver running along, looking for a spine..."
"the most inappropriate appointment since Caligula appointed his horse a proconsul of Rome" (at <i>every</i> mention of Margaret Beckett)
That's about it, I think