i tried it on a friend ds and its works well although its abit of a pain to get the r4 card etc. games works pretty well all the olderstuff like monkey island and indy3/4 worked fine no curse of monkey island or full throttle though.
Considering the very limited raw power of the DS, ScummVM for the DS is awesome. I think that sums it up .
And just to add, it's recently been subject to quite a lot of work to improve memory utilisation so it's future looks very good for the backend. You are never going to get high-res games but for your early SCUMM, Simon etc. it's great (esp. on something like the DSXL).