This is my first time using Horizons Math. My daughter really enjoys this curriculum. In fact, she has gone from saying she doesn't like math, to saying math is fun. I like the spiral concept and my daughter loves that she is constantly learning something new. My only complaint is the teacher's manual. It tells you what to teach but does not give you examples or pointers in how to teach a new concept. For the most part it isn't an issue as it's all pretty basic, but I worry as the concepts get more advanced. Sometimes a child may not grasp an idea and additional teaching insights and information would be helpful.
My son has used Horizons Math for the last two years and has done very well with it. And he wants to use Horizons 3 for next year! My son (age 7 when using Math 2) likes the varied exercises and the colorful pages and pictures. The workbook introduces new concepts in such a way that he is able to read and do the work with little help from me. The relatively short lessons are nice so he deosn't get too bogged down. Since this was the second year using Horizons, I made a few tweaks and decided the teacher handbook was a bit bulky for our needs. (Lots of teaching guidance and extra worksheets are included.) Others, however, may like it for the tips and suggestions on teaching and more hands-on learning. All in all, we have been pleased with Horizons!
This is an excellent program if your child is 'mathy'. It is colorful and interesting and the spiral learning is really great. What it is NOT great at is the concrete aspect of math. If your child is not 'mathy' then you should look elsewhere. After using Horizons 1, my 6 yo is doing great. My 7yo is struggling with some basic math concepts. I am switching to Singapore next year and I cried when I received the boys' books from Singapore math. They give so many ways to understand the concepts completely from concrete - pictoral - abstract. I might have stayed with Horizons for my mathy kids but Singapore looks to be so much more superior in complete understanding that I replaced all three boys' math curriculum with Singapore for K, and 2nd grade.