I hated this book. I read Gina Ford etc all before I had my baby. I then quickly realised that none of it actually works in real-life with a real baby. My baby wouldn't follow the Tizzie Hall routine (funny that!) and it made me anxious and depressed. I struggled to understand what I was doing wrong. Of course, I was doing nothing wrong. I do have friends though that swore by this book.
My advice would be to follow your instincts. I would say though, her self-settling information was reasonably useful. I did try and get my baby to self-settle as much as I could. But her ideas about routines and bedtimes etc, I thought were rubbish. I always like how she would say "wake your baby at 11am". Hah!!! Like babies are robots.
I ended up getting a sleep and settling specialist in to help me and her advice was great. Basically the only thing she said to do was start a little nighttime routine where you put the baby down in their cot at roughly the same time each night (say 7pm). But even then, the baby was 7 weeks when I saw her. I did find that helpful though. I woudl do a little routine at night and feed the baby in my room with the lights dimmed.