This homeschooling website has an article about Singapore Math that is short but informative. It tells a brief history of Singapore Math in the US, then goes into why it may or may not be the best choice for a homeschooling curriculum. Here is an extract from the article:
The curriculum uses a true spiral approach, a method that is used less successfully in the United States. In the spiral approach, the curriculum assumes prior mastery of the subject in the previous grade and so does not review basic processes but moves on to a higher level in each subject. If single digit addition is learned in grade one, then it will not be reviewed in grade two. Instead, double digit addition will be introduced and taught.In the United States, the student generally has a review of basic concepts each year before moving on to the next level of learning.
I think the article’s points are good, with the exception of the idea that all of the curriculum is consumable. With the textbooks, it is possible to reuse them (though as paperbacks, they can take a beating) and have the students copy their answers into math journals or separate pieces of paper.