It was brilliant. I ran with my friend Mike -- here we are, at the finish:
...and we got round faster than I expected, finishing at about an hour and ten minutes. The official times still aren't all up, so I'll probably find out the exact time tomorrow.
Full debriefing on my running blog, if you're interested!
1 Just as well, as the bloke who won it did it in less than half an hour, which means he could have easily gone around twice and beaten me!