My DS10 has just started this. We are new to homeschooling so I don't have much to compare it too, but here are my thoughts.
It covers a range of biology topics, including cells, classification, studies of the plant and animal kingdom, the body, etc. There is little pre-planning required on my part. You do need to purchase at least one of the additional texts that the reading assignments come from though...I purchased all 3 because they are great resources in general. There are a few units where I am not crazy about the lab or activity suggested, so I am just going to add in my own.
You could get away without purchasing the student book and copy some of the pages out of the teacher guide, and just keep a notebook with it. I think this curriculum is a good fit for my son's age/stage. It would be easy to add more to it if you wanted to get more in-depth in any topics, and they give you suggestions at the end of each unit for doing just that. I'm sure that my older DS, who is 12 and a complete science nut and is working through chemistry and physics this year, is going to want to go through some of the units in this curriculum too.