Well, they include an error metric in the paper - basically average vertex distance of predicted face and actual face model (in interocular distance units). The

Well, they include an error metric in the paper - basically average vertex distance of predicted face and actual face model (in interocular distance units). They seem to show that they are much better than state of the art with respect to that error, but of course if you want to interpret what that actually means then it's probably easier to interpret the error with your suggestion of actually visualizing it.