Completely agree re comments about gf and exclusive b/f. DD1 slept through only once solids were introduced at 4 months. DD2 got solids at 6 months (thanks to the new WHO guidelines!!), and didn't start sleeping better until then.
She actually doesn't sleep all the wall through yet, waking between 4 and 5 am for a small drink of water and a cuddle before going back to sleep until 7. However, she's got 3 teeth coming through, and already has 3 so has been teething for what seems like ages.
I would be interested to know how many of Gina's babies were exclusively b/f for more than the first few months, because I don't think some of the feeding routines are as feasible once they get a bit bigger. I notice that her revised book now mentions the fact that b/f babies may take longer to get into a particular routine - this was not mentioned in the first edition I used with DD1, so perhaps she had feedback from readers to this effect.
There are lots of gf threads on here - my advice would be go with the general principles as they give you a pretty sensible overall structure, but don't get hung up on them. In particular, don't worry if baby doesn't do the 'right' thing one day. They will eventually find their own rhythm. As someone who likes structure in my own life, though, I found I was a much more contented mum for following the routines, partly because I felt I had some sort of control over my life again, and partly because both my children have been genuinely happier with regular naps, feeds and playtimes.
Good luck with whatever you choose to do.