My daughter loves the Horizon math books. When I mentioned that I was looking at other math curriculum for next year, she looked sad and said, "I like HoriZONS" (the way she pronounced it, lol). She loves the colorful pages and pictures.
I will make the comment that, because Horizons is a spiraling learning method, where you continue to add new concepts before mastering the last, it is not for every child. My daughter is thriving with it, but my son is struggling, which is why I am looking into something else for him for next year.
But we have loved our last 3 years of using Horizons, and wouldn't change it for anything!
I have used Horizons Math for my last 3 children and it has been able to meet all needs, I have one slower learner, one excelled learner and one average learner and all three have greatly benefited from these workbooks. I was also very impressed with how high the kids standardized test scores were in math while using this curriculum. I also love that there are Biblical reference throughout each book.