Try the Preview version of Power View HTML5 in Office 365 Sites.
When you create an Excel 2013 workbook with Power View sheets, you can save it to SharePoint Online in Office 365. Workbook readers can then view and interact with the Power View sheets in that workbook in brwoser. Currently, by default Power View renders the Silverlight version. We have recently added a switch option which allows you to try the preview. You can view reports on any HTML5-friendly device. This is a preview version, so some of the visualizations may not work yet or features are not complete. You can always switch back to the Silverlight version for those cases. But we feel this is good starting point for you try and explore and get a sense of what is ahead. We appreciate your participation and feedback. Please try out and provide your feedback here
Power View Silverlight with "Try the Preview" option
Power View HTML5 with "Take me back" option