I thought both Ninja Gaiden and LoI had pretty great combat systems. It's pretty funny that both also shared the same flaw of horrible level design (LoI suffering more so in this regard). I think when they do compare it to GoW, they are specifically just referring to the way the Combat Cross works and the QTEs though. It's pretty blatant in that regard. Elsewhere, well, the game tries a bunch of other stuff. So I wouldn't call it a ripoff of GoW, because it's really a mesh of different games, incorporating a lot of different game design elements, principles, and ideas. If it works well remains to be seen.