Despite being quite the average geek, I've never been that much into Pokemon. It's not because I don't like it, but rather because it became popular when I was in undergrad and had a lot less time to devote to shows, games, etc. Still, I've always loved the characters and went into the movie with an open mind. My reaction? Awesome.
In my completely spoiler free review, Detective Pikachu shows us a world where humans and Pokemon live side by side and does it superbly. The animation is top notch and there are almost no points where the Pokemon don't seem so naturally part of the scene that you forget they're not actually there. Each one translated into 3D very smoothly and seemed (from my limited Pokemon background) to represent their particular traits authentically. There's little more important in a movie like this than to get the design and character right… as in "authentic to the established world"… as in NOT whatever the hell this is:
Point being, this was a really good movie and a good Pokemon movie from what I can see and I highly recommend it.