I'm in the minority here. I think the new form looks awesome! I, too, get the DBZ vibe from it, and to me, this is a good thing. Mewtwo's always reminded me of Frieza anyway. The "tail" coming out of the head, to me, looks more like an extension of the tube that normal Mewtwo already has coming out of his head, and I see purple lines that, to me, look like a real tail, just longer and skinnier. The whole thing just looks like a more advanced creature in general, and looks just as good as the original Mewtwo, imo.
That being said, I have a hard time believing that this is real. First off, the fact that we have 2 pictures of an otherwise unheard of Pokemon appearing at once. If it was just once that got leaked, I'd be more of a believer, but two of them so close to each other just seems like someone trying to force authenticity. That, and there is no better way for GF to piss of Genwunners than to change Mewtwo. The change would be sure to split the fanbase, which would be no good for business.