I would echo aeh's recommendation for AAS. We found gaps -- massive gaps -- with DS in level 1, lesson 1. Then it was really easy/trivial through the next level and a half before we found more gaps, after which is was pretty slow going.
We were doing this through the process of getting him ID'd for an IEP at school. So after going through the first 2 levels, he did a lot of the detailed phonological testing. I could very clearly see which parts of it that AAS hit, and what it did not. While he showed huge improvement on word segmenting (AAS teaches this), he still bombed manipulation of phonemes tasks, and AAS does not do very much of this.
DS enjoyed working on AAS as well: I pretty much promised that it no part would ever feel very hard, and that spelling and writing would take less effort if we did it. With those promises (both were true), he dove in with enthusiasm. M&Ms might have been part of the equation as well...
