I have spent the last five months or so working my way through it and finding where the gaps are in my research for me to fill.
It has been a brilliant aid because as I fill in each person I spend some time looking at the gaps I have and quickly seeing if I can find details. My plan is to spend more time when the whole book is filled, doing extensive gaps. However it is amazing what a 5 minute quick search can bring up.
My great x 4 grandfather Corles Baldwin and his wife Esther are parents to Thomas born 1815 in Ireland who emigrated to Canada and William Henry born 1829 in St Giles in the Field, Middlesex, (my great x 3 grandfather). There clearly must be other children between these two. I decided to check the baptism records for St Giles in the Field which are now available as part of my Ancestry sub.
Eureka! I found another 3 children! William born and died 1823 at 2 months old, Sarah baptised in 1824 and Henry baptised in 1833 and died in 1834 at less than a year old. So my William was not the youngest child and it also gives me another clue as to when Corles and Esther came to England, before 1823.
More research to do later this year! A possible marriage for Sarah as I was unable to find a death for her as a child for starters. Other families are proving as exciting as I work my way through the book.