It’s a genuinely enjoyable film, something I'd happily watch again and feel comfortable suggesting to others. To be completely honest, I'm not certain this will resonate with viewers who are devoted to Sherlock Holmes, though it does broaden the world associated with that character—it’s up to each person to decide if they want to engage with it. I am a fan of Millie Bobby Brown ("Stranger Things"), and her performance here demonstrates she is more than able to not only headlining a film but also sustain its momentum throughout. Even though the supporting cast seems almost inconsequential, the movie ultimately works well. I did find the fourth wall breaks distracting; it felt as if she was either addressing an off-screen production team or posting on social media. The shifts were somewhat abrupt, and they obviously draw from Sherlock’s visualization methods seen in previous films, but with a different approach. I genuinely thought someone should have checked to see if she was alright, similar to what happened in "Dora and the Lost City of Gold." A narration track describing her actions would also have been acceptable, though I appreciate the desire to try something new. Aside from Burn Gorman, who delivered a solid performance as the antagonist, and Frances de la Tour, whose portrayal elevated the “worried grandmother” role, everyone else seemed somewhat disengaged. Perhaps Sam Claflin fulfilled his part exactly as intended, and Mycroft is meant to be that uninteresting and frustrating—but Henry Cavill appeared to be glad he wasn't required to have Sherlock perform any significant reasoning; he simply needed to appear mildly interested in what was happening. Despite its flaws, there’s a good film here, which is disappointing because it had the potential to be truly exceptional.

Source on TMDB