To be honest I think initiate slow sales was always on the cards, mainly due to the DS demographic and while I'm sure they have lost a fair amount to R4 I don't think this it has had that much impact,
I have been a big fan of the DS and have enjoyed GTA on various formats but at this moment in time I'm not gonna spend over £25 to play it on the small screen no matter how interactive it is.. to me the DS is there for plane journeys and when i want a light break from reading on the beach so hopefully when I'm next at the airport and my Girlfriend is checking out the perfume I will be checking out China Wars in Dixons