Well there is one thing to be sure about. GTA:Chinatown wars hasn't underperformed because its a bad game. The game is a gem for the console on many fronts.
My core gaming group of friends have all tried out the game. Only 2 of us brought it, the rest played our copies for 30 or so minutes, one decided to pirate the game :(
I know a-lot of DS owners either as being directly friends or via co-workers at work. I have to say most of the owners are either seniors (50+) or under 16 (game is R16 in NZ). they easily out number my core gaming group (just 6 of us are hardcore gamers, but we're all mid to late 20s).
But here is my gut feeling (as I can't really can't prove any of this with statistics).
in NZ, the game was poorly advertised, nintendo products normally are but in NZ it was really bad, I had to tell my friends that the game existed. Nintendo DS's market I'd say is filled with kids and seniors along with casual 20-30 somethings who have the DS for mario or generally aren't interested in mature games at all. The Hardcore I'd say are out numbered.
The GTA:CTW owners are most likely also GTA4 owners (I am), I honestly wouldn't be surprised of alot of owners that already have GTA4 flagged buying the game because they already had GTA4 and are happy with that. Reason's for flagging it could be either being happy with GTA4 for now or disliking the DS's graphics and/or the play-style of the game (top down perspecitive).
Piracy could be a reason (not the main reason). I already had a friend who pirated the game, and I'm expecting that to grow by at least 1 more person. with a recession (the R word), I wouldn't be at all surprised if the hardcore DS players are pirating if they can and saving their pennies for this seasons must have games.
