Not surprisingly, this gen's new pokemon are a disappointment overall like the last two gens. There are a few winners like the tree and Aegislash (cool ability), but come on. Keys are a pokemon now? What's next? An Alarm Clock pokemon? A telephone pokemon? A magazine pokemon? Only 1 new poison type that's not only exclusive to Y and but has an underwhelming design? And I don't like the pseudo legendary. I'm not a fan of the design, It's typing is lame, it evolves at level 70 which is all but assured to be post game, and it's stats aren't really that impressive for a pseudo legendary.
I'm not sure how I feel about Megas. Most designs are ok but idk if I'd like it gameplay wise. Someone speculated earlier that you could visit Kanto, which if true would be awesome, but someone else said that post-game is limited, so it seems unlikely to me. I'm 50/50 on the game right now, played every gen since the original Yellow in 1999 and bought them all except gen 4, but at this point it seems unlikely for me to buy it. Maybe used down the road.