Wonderful network isn't the word is use for it. It's more of a patched together hodgepodge. One minute you are on a nice bit of road, the next you are diverted on to some weird alleys round the back of a housing estate. Then you can't see the next sign so you make a guess and hope for the best. Then you say fuck it I'm just riding on the road now.
I'd say it's 90% (by mileage) good, and I've cycled a few thousand miles of it so that's based on significant experience. But there are certainly poor quality bits. Sustrans is currently doing a mile-by-mile review of the network with the intention of bringing it all up to a quality standard, and withdrawing those sections which can't reach it.
