Maxwell Alexander’s review published on Letterboxd:
In the long run this seems like a good vehicle to showcase the young Millie Bobby Brown's talent. The aim of this film is towards a young adult audience who haven't already been taken in by "Sherlock" or the RDJ series. It is harmless while having some notable charm.
Director Harry Bradbeer is famous for his excellent work on "Fleabag" which he tries to bring that style here to less success. Writer Jack Thorne is not as elegant as Phoebe Waller Bridge so his fourth wall breaks littered throughout the script are clunky and unnecessary. It pads the runntime at about 2 hours which feels too long for this story.
It really is "Sherlock Holmes" lite. Other than Brown's performance this film doesn't stand out to me. On a side note I would pay to see Henry Cavill play Holmes proper in his own story.