My brother studied in Halle and I went to visit him repeatedly. During all those visits I never went to or noticed the Francke Foundation Buildings. Halle itself is not that touristy, and this site specifically even less so.
What I enjoyed about it was that it's not a museum. The schools founded by Francke are still in operation, 300 years after the fact. Quite a feat for a foundation.
Due to this being an active school, several parts are not open to public. There is, though, still enough to see. The library is interesting. As is the tiny museum showing items from all over the world in order to support the studies of the students according to Francke's ideas.
OUV
My gut feeling is that it hinges on this being one of the earliest privately founded schools in the world. Also, the school is still in operation and Francke's ideas influenced how Prussia set up its schools. From an architecture point of view it's certainly not a WHS.
Update: Germany decided to retract the nomination upon the very negative ICOMOS evaluation they got.
Getting There
Pretty simple if you happen to be in central Germany. It's a 15min walk from Halle Main Station.
Personally, I enjoy Halle old town. The area around the Saale is quite nice, too. And Halle forms one metropolitan area with Leipzig, also very nice. Halle's outskirts, though, are really ugly, most notably Halle Neustadt.