Mario Party DS does the series more than justice.
First off, everyone's favorite heroes are shrunken to the size of hamsters by Bowser, respectively. As a result, all five of the game boards (as well as each of the mini games) take place in a larger-than life setting, which adds an extra dimension to both the gameplay & the game's story telling.
For the first time, the single-player mode takes center stage. There's a prevalent storyline that orchestrates the game's circumstances, and gives each of the party boards meaning. The characters get roped into having "parties" in order to defeat the Bowser-minions that have taken over the 5 boards.
Mario Party DS combines the best elements of the last 8 games with a brilliant storyline and the best mini game collection in the series to date. Single-card multi-player is the icing on the cake.