>What are the advantages of creating a dataset as a class?

When you build a dataset with the designer, the generated class allows you to use strong typing and intellisense.

Consider the following code (with custom DS class)

MyDS ds = new MyDS();  // my custom class
...
foreach (MyDS.OrdersRow row in ds.Orders.Rows) {
    row.CustomerID = cusID;
    row.OrderState = 1; // 1=Pending
    }

with this one (generic DataSet)

DataSet ds = new DataSet();
...
foreach (DataRow row in ds.Tables["Orders"].Rows) {
    row["CustomerId"] = cusID; // undetected error here! field name 
is "CustomerID"
    row["OrderType"] = "Pending";    // wrong type
    }

Not only the first option is easier to type (intellisense avoids the need to remember each table/column name) but it's also safer: the compiler will check the existence and type of each member.

Regards,