Can it do mesh routing in the same way as tinc? Otherwise it's a poor replacement. It was not immediately evident in the three or so minutes I took to look at the project's web page.
So, I think WireGuard can't, but it can be used as a part of the puzzle. I'm running a mesh using WG as the security layer, and then l2tp to provide a layer 2 on which to run batman-adv. I have a bunch of machines getting DHCP addresses from my home router that way, and (I assume) batman gives me good routing. Of course, cobbling together your own "secure" mesh probably isn't ideal, but it works surprisingly well.
Mind providing more details on your setup here? I tried throwing together an overlay network using OSPF, but never really got it off the ground. I'd love to hear what you've got here!