My software uses it to send video, audio and metadata from a C++ server to the browser. I found WebRTC to be an nightmare causing this feature to take months longer than expected to implement.
Originally used googles WebRTC but it didn't offer enough control, now we use libdatachannel. Getting the peer connections setup, getting what we wanted out of the SDP negotiation, restructuring the video and audio data in the correct format were some issues I remember running in to.