If you can find an alternative guide to these cananls, then take it. I will give it 1 star because the spiral binding and the clear colours on the maps make it easy to read while actually navigating, but it is poorly presented and inaccurate. The text is an untidy mixture of practical information and background about the canals, that would be far better if separated. Useful information about distances, for example, is difficult to access.
Most importantly the information is out of date and there is no indication that the information can be guaranteed only at the time of the publication. We went to visit the church in St Martins to see the boxed pews, which had been removed 20 years previously! Despite what is said in the book you DO need to book to enter the Montgomery canal. Important information about opening hours, footpaths and accessibility are missing.
One thing that is true is that the lock master at the entrance to the Montgomery canal is Colin Payne and he is indeed a mine of really useful information.