Lumo has a long, sometimes entertaining, and frequently informative rant on EM Drive today. He thinks it and the publicity it is getting is nuts, and I'm pretty sure he right. I guess nearly every physicist is going to stick with Newton on this point.
Of course he adopts his usual dogmatic style, dismissing, or rather ignoring the possibility that some genuinely new physics might be involved. While I am virtually certain that he is right, I don't think that that is the right attitude to adopt toward claims like reactionless drives, cold fusion, ESP and so on. One should probably ignore such things, but if you choose not to, I think that the right attitude to adopt is Einstein's, namely that those things can only happen if some genuinely new physics is involved, and think about what that might imply. Usually, it implies a bunch of things that violate well established laws of physics and a lot of nonsense.
In particular (as Lumo and others have noted) it implies either that the whole of mechanics is bogus or that slightly odd configurations of electromagnetic fields can couple rather strongly to some previously unknown fluid. If you believe that (and I sure as heck don't), you ought to find some more fundamental method of investigation than building big microwave cans.