I'm not a Pokémon fan, so I can't say how it looks compared to other Pokémon titles, but I do think it's pretty ugly.
To be fair, I've watched the trailer a few times, and it barely gives you a look of the outside battle stuff. So maybe it's just a really bad trailer.
I usually love cute chibi art styles, but what I've seen in the trailer does not look cute to me. Their shape looks pretty rigid and stocky, like a Funko Pop. They don't seem to animate well, and they don't look very emotive, giving them a creepy doll-like appearance (but, again, this is based on limited footage from the trailer, so maybe they do have varied facial expressions and animations we haven't seen yet).
It does look kinda like a generic phone game, lol.