The debate I have heard about DataSets is not directly related to a 3-tier architechture, but rather how long that object will persist in the world of Microsoft. Imaginge 8 years ago designing an elaborate Business Layer built on passing ADO recordsets around; that code is probably outdated and somewhat useless now.
The DataSet is a step up in that it is actually just XML which should hopefully persist for a while but may someday also be obsolete. The argument I hear is to use more prmimitave types like arrays and such to pass data along, so that when Framework specific object are obsolete the transition will be easier.
With that being said, I still take a chance and use Datasets passed back from the DAL, that are then used upward however needed. I think they are nice to use and I still prefer them over other types.
