I really really dig the art style. For some reason I was thinking this movie was going to take place in "the real world" so when I saw the "Sinnoh League" poster in his bed, I got chills. The world building in this movie is next level and seems to have been done by some really dedicated Pokemon fans.
One small gripe about Pokemon I've had, ever since I was a kid, is that it lacks any sort of contextualization. So, it's always on the player to imagine encountering a wild Pidgey or clearing space to have a battle with a random trainer. Attempts at introducing context to this world are usually pretty poor ala the mainline Pokemon anime which kind of breaks the world to present a weekly anime instead of accurately portraying the world fleshed out in the games. (That's why I liked the Origins anime so much!) This seems like a really cool way to present the Pokemon world in a realistic and believable way. The Detective Pikachu angle makes sense because it gives the story something to dwell on outside of Pokemon battles which probably wouldn't have worked with this visual style. So, you're not breaking the world in the way the anime seems to do. But you're still contextualizing and fleshing out the world we've spent hundreds of hours imagining since we were kids... and that has me really excited.
We'll see when it comes out but as of right now my hype level went from 0 to 100 after this trailer. Despite the fact I don't think the trailer itself was all that great, I really enjoyed everything that was in it.