There's a great writeup by a Londoner on mtb-wales.com somewhere of their impression of the weeekend, but I can't fid it right now. I've never ridden it but will be heading out to try the Cli-Machx route as soon as I have a bike built.
Its a great enduro, long climb to start with out of the town, then some really good descents, rocky and fast. It uses the same forest as the Cli-Mach but when I did it we rode on different trails. Very good chilled out enduro style ride/ race, there was a band playing at the top of the first climb
When I did it it was a bit muddy (one mate destroyed his entire gear system) but all rideable, just.
You do need to be quick with entering though as it is popular and has limited spaces.