I got my son Xavier a Spectrum Spelling book and I LOVE it! He got his first 100 on a spelling test, he hasnt done that all year. I want to try the other subjects and am curious how everyone else feels about them? I must say I LOVE the price :)
We used them for the first two years, but after awhile I felt that they were just not enough. The second year we used them, they were more of a supplemental book than anything. The Spelling & Writing books we did do just as spelling and writing on its own. It got to the point though, where each year they repeated a lot of the same material and my daughter was bored with them and would fight me every time she had to do them, which is ultimately why we switched away from them. We will use them from time to time as supplement, or go over things we didn't cover in the year after we finish the year's curriculum (For instance we use Math U See, and the spectrum workbooks would have a few things in there that MUS didn't have for another year yet...).
They were tremendously helpful for me as a first time homeschooler on a super tight budget when I was still figuring out this curriculum thing! My kids were little,so workbooks were OK for a bit. It's not a full curriculum, and few kids are designed for strictly workbook type learning.