We used SYRWTL briefly but it wasn't a good fit for my daughter. I still highly recommend it as good solid preparation depending on where your daughter is and how comfortable you are helping her.
If your daughter has good solid English background, it's a great book. If not then you need to be comfortable using the text so you can help your daughter if she struggles with any of the text.
Its one book that really brought tears for my daughter so I sold it on ebay. The reason was my daughter didn't have a good solid background and for her to see some of the classic text and poetry in there it just drove her mad. The book is mainly used in schools by prep school so it really isn't an instruction book that shows you how-to. It's meant to be used by teachers but if the parent knows what they are doing then its fine too. I didn't!
Why not have a look at the sample on GP website. I think they normally provide a whole sample chapter. You can just do that with your daughter first and see how you get on. The books are pricey esp if you get the answer book too so before splurging like we did, its worth trying the sample text first. By the way I am a huge fan of GP SYRWTL series and we have used them successfully in other subjects apart from English. I still say the English one is very good for the right sort of child or for one who has a parent who knows a thing or two about the language.