Well, we love it at our house. But, I should add that I have NEVER read the beginning of the book that tells you how to use it. That only made it seem so very difficult, it discouraged me and almost made me toss the book out.
After I got past the idea that I had to understand the "instructions" we moved on with the book. I still don't use it 100% as it's written. But, we do work through it lesson by lesson following the basic principles of it. My kids love that they learn to read "sentences" so early in the program. We have never used their writing prompts b/c my children have been ready to read before they were ready to write.
I've used this to teach 4 of my children to read already and am working with the next three through it now. The furthest we've ever made it is lesson 60, and that was b/c the kid wanted to keep reading the stories. Finally, I gave her permission to just read the stories through the end of the book and we stopped doing lessons. Though, I did skim through to teach them any of the sight words or sounds that they didn't already know.
It's mostly phonics with some sight words/sounds. They also teach that it's better for the child to NOT know the names of the letters prior to starting the program. Well, my children learned the names when they were TWO... and it didn't hinder them through the program at all.
Hope that helps. I know it's not right for every child, but I'm ever so grateful that it has been for each of mine and pray that it remains that way until I've taught the last one to read! (I don't want to learn a new program! lol)