I have used the deprecated reportviewer in web forms in the past and it has been great. When I tried to create my first HTML5 Web Forms Report Viewer I followed the instructions here http://www.telerik.com/help/reporting/webforms-report-viewer-controls-embedding.html using the Telerik HTML5 Web Forms Report Viewer item template.
However there were some errors reported in the log when the page was created. See attached screen shot.
Error: No class implementing System.Web.HttpApplication is available
Error: Fail to register Global.asax routes.
I am not sure how to fix this.