Honestly, while most aspects of the game mechanic wise and graphics wise were fantastic, possibly the most enjoyable I've played in the series, but one thing that bugged me was the lack of stuff to do post-game compared to say, Heartgold and Soulsilver.
That and I keep getting my ass kicked in online battles...
And if I were to list my favourite new Pokemon, it would probably be something like this:
1.Sylveon. Saved me from dying a lot, and I just find the design adorable.
2.Chespin, but only the first and third forms. Because Quiladin just looks too goofy to me, but the rest of the line is great.
3.Xerneas. By far my favourite of the legendaries. Not only does it do a great job of showing off the new fairy type, but it's so majestic looking.
4.Fletchling line. A really nice idea for a reigonal bird, I love the fire-flying combination (a reason why I like Charizard) and I just like the design.
5.Greninja line. By far the most overrated pokemon of X and Y in my opinion, but even I can't deny that it's badass. Plus I love Pokemon with high speed and special attack.
6.Goodra line. New Dragon type? Looks adorable? Purple? My kind of pokemon.
7.Espurr line. Literally just a case of liking the designs, plus it's a rare thing for the series, a cat pokemon I actually like.
And those are the ones on the top of my head. Keep in mind, I'm not a competitive pokemon player or anything.