For a regional dex, sure. But there's no national dex on this one. The models for the other Pokémon might not even exist in the Switch generation, though we won't be sure until the game is properly datamined.
Seems insane if like 2/3rds of the first gen is left out TBH, specially with the whole Pokémon Go stuff and all.
The models are just the ones from Sun/Moon reused, they haven't been changed. Animations as well, even the ones for the new Pokemon camp feature were in Sun/Moon.
Its not bad at all really, its plenty for a single player exprience - And I do agree it looks VERY dated, but speaking only from my personal experience with the game, I enjoy the competitive multiplayer the most. Previous games have showed me that I really dont care much about the characters and story (specially in sun/moon) but I still enjoy the competitive game, and having the roster reduced to 400 tells me many stablished "usable" mons will be left out. And yeah, thats a bit of a bummer.
I read some time ago that they might add them with patches and updates, so Im gonna wait to see if theres any update on that.
They deconfirmed that a while back, there will be no post-launch updates.