John Mighton, the author of the book, is the founder of the JUMP Math programme in Canada. I've used many of his ideas in the classroom, and I've found that they empower children. They take a problem that might seem unsolvable and they give a child a way to approach it. One of the simplest of his ideas is giving children a structured way to 'count on and back' (including counting in multiples), using their fingers. We call it 'using fist numbers' (I'll write more about it in another post).
Now - this isn't a strategy you'd want your children to be using for the rest of their mathematical career. But it works - it is a reliable and efficient way to solve simple problems (while we continue to work on automatic fact fluency), as well as a great way 'in' to harder problems. The sense of achievement children get, both when they have a 'tried and true' strategy for solving simple problems and when they can use that strategy to work with 'big' numbers, shouldn't be underestimated. Several of my Primary 1s, for example, were able to use this 'counting on' strategy to accurately add sums like 22 + 15, without having been asked to tackle sums like that before. Again - I'd rather see them move to more efficient strategies (like those suggested in Number Talks) - but you should have seen the smiles of delight and the cries of 'This is easy!' when they managed to solve this difficult sum all by themselves...