My issue is exactly the same as Mr. John Ortega's described here.
However, both of the proposed solutions have not worked for me.
If I replace "Report.aspx" with "ReportViewer.aspx" in the Report Manager URL (ex: "http://servername/Reports/Pages/Report.aspx?ItemPath=%2fFolder+1+Name%2fFolder+2+Name%2fReport+Name"), I'm given a 404.
If I use the Web Service URL structure instead (ex: "http://servername/Reports?/Folder 1 Name/Folder 2 Name/Report Name"), I just get redirected back to the home page of my report server (which is "http://servername/Reports/Pages/Folder.aspx").
So I'm not really given an opportunity to pass report parameters via URL parameters, because the report itself won't come up.
http://servername/reportserver, then to your report - you will get the correct url with reportviewer.aspx - user1578107