Well, with all due respect, I'm not sure that three days is enough time to know whether or not Singapore is a great program or not, particularly with a child who has not been accustomed to that pedagogical approach. Like I said, it doesn't work for everyone, surely, but I've known a lot of fairly mathy kids for whom it DOES work well.
The nice thing is that it's pretty low cost to try-- so you haven't lost much if it doesn't seem to be a very good fit. One caution, though, is that it assumes MASTERY of previous concepts, so starting with 3A can be difficult for students who haven't done 1 and 2 via Singapore as well. It may be useful (if you're ordering anyway) to pick up earlier (inexpensive, softcover) textbooks so that you can run through a quickie review.
What I like about it is from a pedagogical standpoint-- it's solid in terms of teaching about math as a set of USEFUL TOOLS. It introduces higher concepts appropriately-- when kids have a good foundation for understanding them-- and spends VERY little (if any) time 'spiraling' or delving very shallowly into concepts only to abandon them illogically. It's a mastery-type curriculum, and it's also based on the kind of thinking about numeracy and mathematics which is the basis of later applications-- in discrete mathematics, in stats, in calculus, and in advanced mathematics.
We didn't use Singapore blindly, by any means-- but it does prevent the kinds of conceptual gaps that can otherwise develop without something intended as a complete curriculum.
We didn't use ALL of the workbook problems, by any means. Often just 10-15% of them were plenty of "practice." We DID find that the "challenging word problems" workbooks were a must.
We also allowed DD to work more-or-less self-paced during the two years that we used Elementary Mathematics. I've never been as happy with a math curriculum since, and we've seen several in the six years since. My daughter found everything up until Geometry a breeze on the basis of what she learned in that two years with Singapore Math.
As noted, I really can't comment on MUS or LoF, not having used either in any meaningful way. My DD is a reader, so those approaches SEEM like they should have worked well for her, but she seems to need a more systematic approach to learning mathematics in order to build a full conceptual framework with internal connections between ideas.
