I have been using them for just over two years. So far I have been very pleased with them. The wheels have stayed very true, tyres have fitted and inflated easily. Thanks to the guys at 2pure I now have the newer style rear hub and the sealing is much better than in the previous version. To give you an idea last October I did 5 laps on them in the wet at Dusk til Dawn, I then switched to a bike with a Hope Pro2 SS rear hub and did another 5 laps. When I stripped both bikes down after the race the CB rear freehub was very clean inside, unlike the Pro2 which was full of water. Admittedly Pro2 hubs aren't known for great sealing but I would say the new CB ones are much better. Only downside is the new freehub seems slightly quieter than the old one. Bearings are easy to change too.
Spares don't seem to much of a problem, I needed a new valve last week and 2pure where very quick at sending out a replacement. In comparision I have found Mavic very slow for getting replacements for factory wheels.
I would say slightly expensive at full price, but at some of the reduced prices I have seen they are good value.