I've been using Singapore Math with my 6.5 y/o this year, and it's going well. She fussed a TON in the beginning, until I figured out that she was bored. I skipped her two books ahead, and things are better (okay, she still complains, but it's much less!). I love how the children's names are so much more international than "Bob and Sue"! And, frankly, you can't beat the price. I bought every single book possible for my two kids, and I still only spent something like $40.
Hope you find it a good match for your family!
Mama to four great girls: 14 , 12 , 7 and 4