We switched to this from a more traditional math because it was a daily fight to get math done, complete with tears. As soon as we tried Life of Fred my son begged me to do "just one more chapter, please!" after every lesson.
We have done Apples-Mineahaft so far so I can't speak to the older levels but they are already introducing kids to advanced algebra concepts typically taught in algebra 2. It boots my son's confidence to know he knows how to do something kids several grades higher than him are learning.
The biggest negative is sometimes I have to look at an answer in order to explain how to solve a problem.
If you have a child who hates math give Fred a try, it just might surprise you.
Grade levels used
Fun, engaging and not overwhelming
Some problems are not fully explained in the lessons.
I found Life of Fred to be a great in between for my daughter. She was hating math and struggling. After many different curriculums, I went with LOF. My daughter loved the stories and enjoyed doing math. We did Apples through Goldfish, but then she couldn't keep up with the math facts and really struggled. I felt like we couldn't move on, because she couldn't get the facts down. If you read one lesson per day, it can move too quickly once you get to learning the facts. We had to stop using LOF at that point and move onto something else.
NOTE: If your child is sensitive LOF may not be good for him/her. Fred's parents are dead. His father was an alcoholic and didn't take care of him. His mother died diving into a pool and in a later book, the rate of her fall is actually a math problem. I found that to be rather morbid.
My 9-year-old daughter was really struggling with math. She didn't enjoy it and she didn't understand it. We decided to try Life of Fred and things changed almost immediately. She loves reading about Fred's antics and at the same time she's learning! We started with Apples in September. Now it's November and we're almost done with Dogs. We've been able to move through the books more quickly than suggested because she has most of the basic concepts already.