I am going to share my story about BW and my family. My oldest is 6.5, I have an almost 5 yr old, and a 20 month old. They are all fantastic children.
I was introduced to BW by a friend from church. I am eternally grateful to her for this. She was happening to visit a friend in my town and attended our church service (so totally random timing!) and she mentioned this BW book. I was real tired. My 1st was about 4 weeks old and I was cosleeping at night with her as that was the only way she'd sleep (gasp! I didn't want to do this and didn't like this at all but she would sleep a long stretch at night vs waking up all the time. Although I was so nervous throughout this I never even slept well either so I was still tired:)). She didn't nap well either so I wasn't taking long naps during the day when baby naps (like you always hear you are supposed to!) . She was in a pack in play in my bedroom at other sleep times. The pediatrician and lots of articles said that babies cannot form habits when so young,etc but I just felt like there had to be a better way and if I continued down this road it would be a habit hard to break. Well this friend told me about BW and I ordered the book that day. I pretty much read the day I got it. It just resonated with me and made total sense. So about a week later, when she was about 5 weeks old, I decided that was the end of the night cosleeping. She went into her crib postbath and that was that. The first evening was rough. I was actually so exhausted I went to bed early but I heard from my husband and Mom. But we continued on with the crib for sleeping at night and she got used to it well (by 3 months she went down for the night with zero crying/fussing). This was over 6 years ago and I did not have the benefit of this blog nor the Chronicles group. As you may know the book is sparse on details, it is more generalities. The focus is more on the "why vs the how" and the how is left up to you to implement. So it was a bit of a learning curve. I know I did a lot of things incorrectly and had inadvertently too much waketimes, etc. BUT even saying that things started to get way better.
She slept through the night the day she turned 11 weeks old (fromdreamfeed til 6ish and stretching out then to 7ish AM). And we never looked back in that area! The times she woke up in the middle of the night was few and far inbetweeen. It was wonderful and I felt recharged. Sleep is vital to me and I don't feel well without sleep, nevermind not functioning clearly,etc. I cannot imagine parents who have children who are preschooler age and haven't slept through the night. It would cause me physical issues I believe. So it was a huge blessing to our family. BUT aside from that, I discovered BW is a lot more than just sleep. Initially the lure of sleeping through the night so early is what drew me to it. But i discovered all the rest and how vital it is. Of course my children have moments where they are acting like children and going through various phases, but with BW tools and philosophies they are much shorter lived and we work through them and learn. I have 3 wonderful well-behaved children. I cannot even count the number of times people remark on my girls behaviour. Sure, some is their temperament but I absolutely believe some is attributable to BW. And having 3 kids I don't think others can chalk it up to "good luck". Clearly there is something going on and I believe it is BW.
(And in case anyone is wondering, my last two slept the the night a bit later than my first but they also had silent reflux. It was still early on, around 3.5ish months/4 months. And I also read The BabyWhisperer and Dr Weissbluth's Healthy Sleep Habits Happy Child and blended those books with BW on sleep. I think there was a lot of good info on the "how" from those other books).