I thought this was a really good event. Well attended as well - I'd guess there must have been 12 or so kids and 40ish adults taking part. A real mix of experience - from first-timers to folk who had clearly done this before; and a mix of bikes - mainly MTBs, but a good smattering of CXs.
A well-judged course by all accounts, challenging but not off-putting for beginners, following the paths in the park by Craigmillar Castle - certainly more technical than just going round a grass track, as a good chunk of it followed the twisty paths through the woods.
All in all, it looked great fun. There may be a few CX sales made on the back of that (although it felt more of an MTB event to me) - I certainly fancy one and I was just spectating...
Also, in related news, CEC Countryside Ranger Service were there handing out leaflets proposing/consulting on creating a mountain bike trail in the park.