I personally love this curriculum, because it ...
Is rigorous
Moves through concepts in a logical progression
Focuses on mathematical reasoning & understanding
Has vertical alignment between grade
The workbook has the problems set pages (done in class) and the homework pages to be almost identical. The idea being that students can use their classwork to support their thinking at home. The problems are also placed from easiest to hardest, with the multi step and word problems usually at the end.