I'm disappointed in quite a bit to do with this generation, to be honest.
First of all, Sylveon. The fact that it's type is still unknown hints that they are likely going to add some gimmicky new type, you know, "Light" or "Good" or "Fairy" or something. Plus, the design of Sylveon is boring and uninspired, looking like a splice of Espeon, Milotic, and Victini.
Next we have the starters. Chespin is... okay, I guess. It's an odd design, not really notable, but not necessarily good either. If I do get one of these games, I'll probably choose it, because honestly, it just has the best aesthetic to it and seems like it could be at least slightly interesting, what with it's likely secondary type being Dark. Fennekin looks way too cutesy, even for a Pokemon. I don't like it at all, but I don't really hate it either. It's just not my thing. However, Fennekin does have the possibility of winning back some respect for Game Freak, due to the fact that it doesn't look like it'll be yet another Fire/Fighting combo. Froakie... good lord. It's design is just embarrassing. It's not like Game Freak can't do frogs, either. They've proven that they can create good frogs with Politoed, so why is this thing so ugly? Now, I must stress, the evolutions aren't out yet, so I can only predict what they may be. Who knows, Froakie's final form could be a complete badass. However, just from a first-form standpoint, I'd have to say that Chespin is the most bearable.
Finally, that horrendous Mewtwo form. And, I'm not even saying that giving Mewtwo a form was that bad of an idea. Sure, I generally dislike forms for their gimmicky nature, but a new form for Mewtwo actually had a bit of potential. The original Mewtwo looked very intimidating and alien, and a new form could look even more so. But what do they give us? They give us a strange, ponytail-headed oddball. The new form actually looks weaker than Mewtwo, with the cold, slitted eyes of the original Mewtwo contrasting with the giant, bulbous "ANIMOO" eyes of the new form.
I guess the two version legendaries revealed are alright, I certainly don't hate them like I do the new Mewtwo form, but I certainly don't like them either.
To be honest, though, none of this really surprises me much; I've been losing interest in the series once Generation III ended. It just seems like the generations have been getting worse and worse. I fear that some day soon, Pokemon will become the new Sonic: Old, tired, lacking in creativity, and in desperate need of ending.