Installation is a little complex, see the instructions.
Here is the new interface user guide.
Here is a handy video that demonstrates the interface and its features.
So where is this all going? It looks like Oracle are getting serious about the integration of Stellent into WebCenter, which would ultimately mean the retirement of IdocScript in preference for ADF & JDeveloper. It's been a while coming, but here it comes.
Speaking of integration, there's also a WebCenter Sites integration component that now comes standard, a content duplicator that looks a lot like the demo created by uh, someone like fishbowl (I forget who.)
Here is the SitesIntegration guide.
*** UPDATE ***
OMG THERE ARE NO VISIBLE CONTENT IDs? Instead the three non-customisable search result templates only display the filename and the title (which is usually just the filename.) #facepalm