Asp.net and datasets

[reachpradeep]

ive heard alot of arguements for and against the use of datasets in a asp.net website but have now got a bit confused on what the best approach is to when developing a standard web app.

do u think it is appropriate to use datsets to replace the traditional business object classes in the web environment?
e.g a Customer class would be replaced by a dataset datatable called Customers.

ive have heard that some developers replicate there whole database structure into one dataset and make there website run off the datasets. so basically have the whole database in memeory.
what are the issues when doing this? first thing the springs to mind is that you would chew up the server memory, but what if there isnt that much data in the db?

you thoughts?