Personally speaking, I'm excited for the direction Sun and Moon is headed in terms of overworld and battle design. I feel each generation has slowly been progressing to this and that it will slowly improve over future generations. Stylistically it kinda reminds me of a PS1/early PS2 RPG. Pokemon's art style has always been pretty bland so I don't mind the style. Although as someone mentioned a game based on Hawaii should look a lot more lively but it's GF so....
I've been betrayed too many times by getting attached to a 1st form starter that ends with a terrible final form. 1st Gen, I went with Bulbasaur because it was my favorite but Venusaur is my most disliked final form of the three starters. 2nd Gen, I went with totodile but all the final forms of the Johto starters weren't great. 3rd Gen, I stuck with Treeko and was happy with that even though Grovyle was way better than Sceptile design wise. 4th Gen, I was gonna go with Piplup but Empoleon is trash so I went with Turtwig. Gen 5 I went with Oshawott even though it's final form was kinda lame. Gen 6, I used Chespin and was pretty dissapointed but as someone said if its final form had been recolored it would've been a lot better. Gen 7, I'm undecided. Rowlett and Litten both look good but they could easily be disasters when they evolve. Popplio, I have no feelings either way about. I'd love for it to be the Oshawott final form we should've gotten lol.