I have this problem with Excel Services in SharePoint 2013. I have configured Excel Services, and upload Excel workbook to Sharepoint 2013. It is showing well (it's working) when I try to open workbook in browser. So, I then created page with some pagelayout (I am using Business Intelligence Center type, and I have enabled Publishing features). I added a Excel Web Access web part on this page and provided URL to my workbook, but web part is not showing (rendering) my workbook, it is showing a link instead. This link, on click opens excel services with my workbook. This problem happens on every layout (Article Page, Welcome Page) which I try to apply on page. For just a sec. I can see a little white rectangle in left corner of the Web Part, like it is trying to show workbook, but it is gone, and just link and empty space below (on which should be workbook) remains.
I have also installed SP1 for SharePoint 2013. But still of no use. I have also enabled the Sharepoint Server Enterprise Site features at both site collection level and site level. But still the same problem persists.