I don't see how this guy neuters Yi Shan** any more than anyone else, since I believe Yi Shan** runs best playing strings of attacks, and spamming Stun attacks (or manufacturing Stun attacks with his Tiger Claw in the momentum), which matches up pretty well against it. I'd also like to point out that this character may actually make people run him off Water (though I agree with the consensus that All and Chaos are still better at the moment). However, the utter lack of committal protection available to him means his E won't really see all that much play (once per turn max in most games, if that), except as a problem matchup for the Fire bruiser deck who tosses out throws for some redonkulous damage, and hey, who says that's a bad thing? Plus, they can deal with him by packing attack with healthy Stun ratings and/or targeted committing (hellooooo, Zi Mei's Wheel Kick and Pommel Smash ), so yeah, he's nice, but there are answers to him already.
Also, this guy marks the resurgence of grey-area characters, BUT he's minus the protection which made the game so boring to play pre-rotation. So yeah, they can be beat on now.