I first started sewing clothes about 18 months ago, beginning as I suppose most do by buying standard commercial patterns. I discovered this book about 9 months ago, and it has allowed me to improve my techniques amazingly, and has boosted my confidence. I now use commercial patterns as rough cutting guides only, and follow Betzina's techniques to stitch things together.
The results I've found from this book is that I can now make items that are far superior to most you can buy (and I am talking about expensive ranges costing a hundred pounds plus for a pair of trousers)! The clothes fit well and they are finished to a high standard. I've just followed her instructions for shaping the underarm of sleeves, with the result that, for the first time in history, I have a jacket with sleeves that don't pull or feel uncomfortable! She also has an excellent tip for non creasing trousers - underline with organza.
I think the secret to using this book is to work through her techniques gradually and add new ones to your portfolio of weapons one or two at a time. You can really take it as far as you want, either keeping things fairly simple, or using a lot of techniques on one garment. I'd also recommend getting 'Fast Fit' by the same author to give more confidence in altering patterns.
Betzina has got a friendly technique, and I find her explanations generally pretty clear. She also has unique names for some of her techniques, which add a bit of fun to the book! In summary about this book, if the house was burning down, I'd either have to rescue the book or buy another one pretty quickly!