Did the leaves fall off? Something not working right? Let us know how we can improve the Photosynth experience.
I have previously reported this on Twitter, but am reposting here.
I downloaded the Developer Preview of Internet Explorer 11 for Windows 7 on 2013 07 25 (Thursday)
The first time was on a 64 bit version of Windows 7, so I downloaded the 64-bit version of IE11.
The result was that Photosynth.net continually reports that Silverlight and Photosynth (for the Direct3D viewer) are not installed and sends me to their respective download pages.
The old 3D Virtual Earth control is another that the browser doesn't see.
I thought that perhaps because the browser was 64-bit that the plugins weren't being detected, so later that afternoon installed IE11 32-bit on a 32-bit copy of Windows 7.
Unfortunately, I've met with the same results as 64-bit.
Silverlight is detected + functions in IE11 on other sites, such as Bing Maps' Map Apps ( http://bit.ly/photosynthcoverage ) and the Get Silverlight page ( http://microsoft.com/getsilverlight )
I know that the Virtual Earth plugin has been retired and it wasn't ever Photosynth's responsibility/jurisdiction, but I thought it bore mentioning as it might offer a clue.
I can still get the globe to load by going to http://atlas.freshlogicstudios.com/ and pressing the  key after clicking the map, but other keyboard commands no longer send as they did in IE10 on the same machines days before I installed IE11.
Other instances of the VE control (Bing Maps AJAX 6.3) fail to load completely ( http://virtualearth.natelawrence.net/ ) when they worked just prior to the upgrade.
I do realize that with IE11, you'll be moving to WebGL in both Bing Maps and Photosynth, but I'd still like the legacy viewers to function, as I trust they'll be kept for users who can't run IE11.