I've been using Spelling Power with my kids for a long time, I really don't even know when we started using it but it was on recommendation from my sister, Linda. Linda has been homeschooling since the beginning of time and has lots of good advice.
My kids are all naturally good spellers and readers. At school our daughter Lea was tested as "gifted" in this area and it really doesn't surprise me (I'm not sure what that means, but it was on a letter with a diagram that we received from the school. I guess it means she's a smartypants, which isn't big news.). My older two children started reading quite early all on their own, and Steven started reading later, but again, on his own. I read to all the kids as they were growing, from the time they were infants, but I never "taught" them to read.
A curiosity is this though: None of them read voraciously. None of them really enjoy perusing fiction regularly. They like short stories and articles in magazines; they all read well and comprehend well, but none pursue it with a passion. I have a theory that they would probably enjoy high literature, but haven't taken the time to read it with them. Perhaps the future will prove my theory correct once they are in college.
But, they do/did like Spelling Power. All of them enjoyed this book and I use it mainly as a brush-up because spelling correctly has been important to the older kids, and now to Steven, my token homeschooler.
I've tailored it to fit our very laid-back way of educating. I don't force Steven to write because in my experience, asking a boy to write is like asking him to pull his arm hair out with tweezers. It's tedious and there is lots of moaning and writhing going. So instead, we sit down with the book and I ask the word and he verbally spells it. If he misses a word, he does use the sheets (yes, writing) that I have copied from the book to help him to learn the word(s) he's missed. To my way of thinking that is a wonderful method to learn: teaching yourself what you don't know and cutting out the busy-work.
There are games and activities suggestions if we need the support, and also, in the newer version, there is a cd-rom option now.