I too will support Chris' book, not least because he is a member here but also because the very act of sharing his love of curry cookery demands that support. There is however a dilemma, which is not about Chris but about the process of taking a recipe from paper to pan.
It's a bit like all those guitar mags and videos that promise to turn you into a guitar god. There's lots of competent guitarists around but as ever only the few stand out.
Guitar Video = Recipe Book
Guitar God = A bit of talent and loads of practice
No book can promise to make you a BIR chef. Like the missing 5%, it is not a holy grail.