We started homeschooling 3 yrs ago and I chose Horizons Math for my then 4th grader. I like the way there is plenty of reinforcement of each topic and also that there are extra practice worksheets if you need them. It's easy to use and colorful. My son likes the occasional puzzle or riddle that's thrown in too.
I love Horizons math! The content is very advanced. The presentation is a colorful easy to follow workbook. There is plenty of practice problems for the new topic as well as past topics. Sometimes the teaching explanations are not very detailed and require you to work backwards to figure out how teach. Not a hugh problem if you have a pretty good math background. The major drawback I am facing now is they only go up to Algebra 1 and it is very difficult for me to find an appealing and equally challenging curriculum for the rest of high school math.