I use the College Preparatory Mathematics "Algebra Connections" with my 8th graders. I find it to be an ideal book: simple format, light, focussed and accessible for my students. This is what CPM says about itself:
The CPM curriculum, emphasizing core ideas, active student participation in lessons, and consistent practice of ideas over time predates the recommendations drawn from the TIMSS study by five years. CPM has offered approaches to learning mathematics that parallel practices in successful countries since 1989. CPM courses contain the mathematical content required of each course. The teacher-authors present the material in ways that actively involve students in developing and understanding ideas. Students improve their study skills and build life-long strategies for solving problems that are applicable in most academic disciplines, the workplace, and daily life.