I am also trying to find how to get the parameters that the user has set when they hit the View Report button. But I think this is what happens when you do a GetParameters when you hit the View Report button on the ReportViewer control:
When you do a GetParameters() it gets the values of the parameters of the report that is already generated on the screen. So if you were to change the parameters and click View Report, in your Page_Load when you call GetParameters(), this is looking at the parameters before your new report is generated. So if you wanted the new parameters that the user has inputted, you would need to wait for the report to get generated then do a postback and use GetParameters.
If anyone knows how to get the parameter values the user has selected before the report is generated, please let us know.[:^)]