I wasn’t familiar with the "Detective Pikachu" game beforehand, so I can’t comment on how well the film sticks to what came before. But judging it as a standalone film and knowing a little about Pokémon, I ended up liking this more than I anticipated. The story is reasonably well-organized, even if the appearance of the villain felt abrupt—perhaps they needed some extra preparation. The characters are pleasant enough, though fairly predictable. However, the movie's tone really jumps around! It gets unexpectedly intense and somber at times, which makes Ryan Reynolds’ performance feel occasionally like he’s just there to lighten things up. Be ready for sudden shifts in mood with this one. Nevertheless, it's an acceptable film that Pokémon enthusiasts will probably appreciate.

Source on TMDB