We love Singapore Math and use it at home. The one criticism I would make is that we find it doesn't explain new concepts very well. I mean, the pictures are good to visualize this is multiplication, etc. But I just told my son how to carry numbers or things like that.
Supposedly there's a lot more of this in the Home Instructor's Guide / Teacher's Guide (which we hardly ever crack open ourselves). The full Singapore method is supposed to go from concrete (playing with manipulatives and such) to pictorial to abstract representations / explorations of the same topic.
