Protobufs aren’t new. They’re really just rpc over https. I’ve used dce-rpc in 1997 which had IDL. I believe CORBA used IDL as well although I personally did not use it. There have been other attempts like ejb, etc. which are pretty much the same paradigm.

The biggest plus with protobuf is the social/financial side and not the technology side. It’s open source and free from proprietary hacks like previous solutions.

Apart from that, distributed systems of which rpc is a sub topic are hard in general. So the expectation would be that it sucks.