We're using LOF Fractions right now with DS7 and I would say that at least basic familiarity with multiplication facts is useful, especially for the 2nd half of the book. It really breeze over things like reducing fractions with the assumption that the kid understands that 5/20 = 1/4 because 5 and 20 are divisible by 5. Our work around right now is to let DS7 use a multiplication table to "cheat" with and we're working hard on memorizing the tables (using Timez Attack) simultaneously.
It's also a little light on concept practice, which works great for things that DS7 gets right away, but I find that we have to do supplemental practice on some things. So far it's been easy enough to print worksheets online for what we've needed (reducing fractions and equivalent fractions).
