As one of the most frequently adapted fictional characters of all time, Arthur Conan Doyle’s Victorian London detective Sherlock Holmes has been interpreted in so many ways (as a cartoon mouse, as a Star Trek holodeck creation, as a drug addict, as a vampire hunter) that to complain about the cavalier treatment of the character’s canonical history in Guy Ritchie’s new Sherlock Holmes seems entirely beside the point. For those diehard fans of Doyle’s novels and stories or the classic films starring Basil Rathbone as Holmes, Ritchie’s film may play a little too fast and loose with established mythology. But as a summer blockbuster-style film that happens to open on Christmas, it’s a pretty darn good time, and easily the best movie Ritchie’s made in years.

It probably helps that this is the first movie Ritchie’s directed for which he hasn’t written the screenplay. His recent tendency toward mystical mumbo-jumbo and/or repeating the same tired street-crime clichés is also jettisoned in favor of special-effects set pieces and a propulsive (if extremely convoluted) action-movie plot. Ritchie’s Holmes (Robert Downey Jr.) is no staid drawing-room ruminator; he’s a rough-and-tumble investigator who’s as likely to be found in an underground fight club as taking tea in his parlor. Holmes’ loyal associate Dr. Watson (Jude Law) is likewise quite fond of fisticuffs in this new version, which finds the two investigating the curious case of a condemned murderer (Ritchie favorite Mark Strong) who seems to have come back to life after being executed.

The plot details (involving a secret society very much like the Freemasons) are not important (and become exceedingly hard to follow over the movie’s bloated two-hour-plus running time), but they offer the chance for Ritchie to trot out some recognizable Holmesian faces, including the detective’s sparring partner/love interest Irene Adler (Rachel McAdams, appropriately saucy); overwhelmed Scotland Yard Inspector Lestrade (Eddie Marsan), who calls on Holmes for help with cases; and notorious villain Moriarty, who appears only in shadows, mainly, it seems, to set him up for the sequel.

All of these elements come together with panache, and Downey brings the same roguish charm to Holmes that he brought to Tony Stark in Iron Man. Downey has passable chemistry with McAdams, but it’s really his rapport with Law that carries the film, and Ritchie doesn’t hesitate to wink at the homoerotic undertones of their relationship (Holmes is always keeping Watson from spending time with his fiancée). Ritchie’s Victorian London is gritty but glossy, a mix of Dickensian social realism and fanciful steampunk, and certainly takes liberties with historical accuracy. The director’s penchant for slo-mo fight scenes with hulking thugs makes for an interesting contrast with the buttoned-down time period, and the action scenes are generally exciting and well-crafted.

There’s so much action, really, that you could probably have taken Holmes’ name off the title and made the same movie; he’s practically a superhero here, and the villain’s plan involves nothing less than taking over the entire British government. In that sense, the core appeal of Holmes as a character (his solving of mysteries) has been lost, and for all its spectacle the movie is mostly forgettable. But the actors make it enjoyable while it lasts, and Ritchie seems to have found a new niche for himself as a director of empty popcorn entertainment. Purists can protest all they want; everyone here is having too much fun to care.