Personally, I think we got a gen better than second right afterward, and I don't think anything's beaten that one, but we can debate that topic until the cows come home.
The MegaEvolutions seem to me like evidence that they're trying too hard to add new stuff to the game, but that may just be me. I'm not saying MegaEvolutions in and of themselves are a problem -- I'll probably just pretend they don't exist and move on with my life -- but it seems to me, particularly with cases like Absol and Mawile who deserved real evolutions, that they indicate an odd creative choice that I don't see as particularly useful or logical.
Once the actual game comes out, though, I may find that it feels more natural than I expect it will, so I'm still not passing judgment. I expect that they'll be great games regardless, it's just a question of the degree of greatness. (I will admit that I'm probably thinking far more cynically than I would, if it weren't for the fact that I've been talking to one of my friends who didn't like fifth gen and has become extremely cynical of sixth since the reveal of MegaEvolutions.)