I've had these for over a year now and well over 1000 miles spent commuting through London, I've had zero punctures due to the tyres themselves (only one due to me taking a kerb very badly and pinching the tyre). Cannot fault them, they're worth the higher price!
2nd February 2015: I originally wrote this review on 16 Oct. 2014, and the tyres were already a year old. A few months on, and they're still going strong. Granted I haven't been riding much this winter, but they are still in reasonably good shape, no cracking, and still no punctures.