I'll have a go too.
Too easy - I'll be honest: this part I liked :) . Anything that lets me finish the game without grinding is good for me.
Too few events - It could be too early to complain about this, but IIRC, Victini was distributed right after B and W were released, so the fact that none of the new event exclusives were distributed yet is a little dissapointing.
Lacking in post-game content - I wholeheartedly agree. Last generation basically unlocked half of the region after beating the game, and what we have here is just a city and not even a single route. Not as pathetic as R/S postgame (at least we have a new quest and the Friend Safari) , but it's almost there.
Unstickable characters - I agree as well. Bianca and Cheren had character arcs, you could see them grow during the adventure. These guys however aren't growing. And while I'm at it, Gen 5 did a great job making Gym Leaders more interesting and memorable, but in this gen? Only Korrina ever does something outside being a Gym Leader you will fight and never see again, and that's it.
Boring plot / not menacing bad guys - I agree. There's a pattern that has been in place since Gen 2 where the story basically ends between the seventh Gym and the last Gym, and the rest is more of an afterthought. After seeing this for three generations, I was happy to see Gen 5 throw some curveballs here and there (not to mention B/W's excellent ending) , but Gen 6 brings the pattern back in full force. As for the bad guys, I was not impressed. So, OK, Lysandre wants to bring on mass genocide. That makes him look more like a catoonish supervillain, in the same vein as Cyrus. Ghetsis was different because of the way he operated (in B/W at least) : he brainwashed his own son and used him as a puppet, he hid behind messages of freedom and made his people firmly believe that the crimes they were committing were the only right thing to do for the greater good, while working on his own agenda behind their backs... this guy was less of a ridiculous supervillain, and more like a real-life shady politician, and for me, that's what made him the best villain: he was much more believable and somewhat grounded in reality.
Lackluster new Pokémon - I did like most of the new Pokémon, but there just wasn't enough of them. I loved B/W because during the main story they ONLY used the new Pokémon, it gave me the feeling of discovering the series all over again. Here, all I see are mostly the same old Pokémon I already captured tons of times before, with some new ones here and there, and I'm just not impressed.
The Champion - She did nothing during the story and I never cared for her. At least her team was OK.
My thoughts on X/Y: I liked the tweaks in the gameplay and balance, and most of the new features, but that's pretty much it. The leap to 3D did nothing for me, and the actual content (region, story...) was "meh" at best.