I do not teach math. I've been teaching Saxom Math for four years. I was very much opposed. Format is much different from the traditional topical study we have been used to.
Texts are very dry, without color or flashy wording, very scripted.
I did not think students would respond well. The first year at fifth grade was rough. Most students began in the 54 book. However, students almost immediately experienced success. Topics are introduced and then covered coutinuously.