I got the DS purely to use it with the Brain training games (sad I know) and only problems I've had with it is it recognising my handwriting and voice (but seems to be a flaw with the DS that it doesn't pick up the scots dialects)
Do have another couple of games including Mario & Sonic at The Olympic Games, the obligatory Pokemon Diamond (which has vanished at the moment) and Final Fantasy III, but is mainly the brain training I use to try get the brain up to scratch (and at least it comes complete with Suduko puzzles too
) Patiently awaiting the arrival of Spore on it
Good for passing the two hour bus journey to Uni three days a week