Haven't gotten too far into the game, but it seems you can't buy better/new stuff until you go up in Tamer Rank.
Back to the discussion at hand, ladies and gentlemen...
May be an up and coming good notion that Digimon World DS is high ranked in the range of DS Wi-Fi video games, but it pains me to say that when Pokemon comes out, it will most likely reign supreme. The main basis of Pokemon to begin with was to have two versions with different Pokemon to allow more interaction with other players. Making it an online game would boost it so much. Hell, I am going to get it and prolly play it more than DWDS.
Main reason? Battle. If you can fight wi-fi in any game, it automatically is more preffered. Confrontation is better than cooperation. Why trade/breed when you can kick someone's ass? So, I'm with IGN to the point that the game pales in it's ability over Wi-fi to comparison with Pokemon. It was a good attempt, Bandai/Namco, but you shoulda hit the ball harder.