Just back from a week MTBing in the gloriously sunny Highlands - with Kenny's infamous book.
What I like: the brevity of the text (get the OS map), matter of fact descriptions (no 'radical dude!' rubbish), some amazing and inspirational rides.
What I don't like: some route grading is woefully inconsistent, and when Kenny says it might be 'challenging' it can often be translated as 'Danny MacKaskill found it hard'.
By way of an example. The Inshriach single track route gets 'Advanced' (red) and seemed to me to be spot on. The Loch Fada route also got 'Advanced' and the final descent down Glen Biannasdail is largely unridable. Now, I realise this might be because I am too shit - but I really cannot see how anyone could truly ride a majority of this descent. I reckoned it was almost as hard as the Ciaran path (given Expert+ in Kenny's book - and one I got sandbagged on by the evil Glentress girls a few years back, before anyone told me they were competitive DH-ers!).
In balance though, Wilson's book is about having adventures. This means taking everything the wilds can throw at you. Yes, I would like better grading and realistic descriptions of terrain, but just attempting the routes will get you into some fantastic places.