Copy/Pasting my thoughts from elsewhere.
Dragon Exeggutor freaks me out. Keep that thing away from me.
Ice Vulpix and Ninetails are alright, but I prefer their fire forms.
Ice Sandshrew and Sandslash are pretty cool though.
Oricorio seems like a cute novelty. I probably won’t use it, but I kind of like the fire form I guess.
I’m not fond of Minior’s design, but I think its ability is cool. I also like how its core comes in four different colors, and you can’t see which one it is until its shield is down.
Gumshoos is a step up from Yungoose, but I’m still not terribly fond of it.
Fomantis made me think of Petilil. Lurantis looks like it should be Grass/Bug or Grass/Fairy, although I guess it’s a blessing that it doesn’t have that horrible Grass/Bug typing.
Mudbray is ugly, but I like its evolution, so I still may end up with one on my team.
Ride pokemon look a lot faster than they were in XY, thank goodness for that. Also you can fly on Charizard, which is awesome. Flying on Latios and Latias was fun in ORAS, but the sky was so empty for it to be anything more than a simple novelty.
Totem Pokemon seem like an interesting new addition. I hope they’re harder than wild legendaries and the like, though. It doesn’t matter if they’re strong if they just use randomized moves like other wild Pokemon.
Now that they’ve revealed more about Z-moves, I hope people can finally shut up about pokemon fusion or whatever the anime called it. Ash Greninja freaks me out almost as much as Dragon Exeggutor.