I have read that Action/Comedy movies are hard to make because you don’t want to compromise one genre too much to accommodate the other. “Sherlock Holmes: A Game of Shadows” covers both bases well with a good balance of action and comedy.

Robert Downey Jr., who plays Holmes, is always worth watching. He brings massive on-screen charm. The film crew brings the gimmickry, which provides much of the film’s fun.

The plot, however, is a bit of a mess. But the movie has action galore, clever disguises, explosions, deeds of derring-do, even some opera. Does it all add up? Well, sort of, yes.

“SH: AGOS” has some pacing issues. Some of the exposition takes long chunks of dialogue. Overall, though, the movie gets its job done. That job, of course, is to channel the highlights of the successful 2009 Holmes movie and add a few new wrinkles.

Jude Law returns as Watson, Holmes’ assistant, consultant, rescuer, foil and chronicler. Rachel McAdams is back, but only long enough to pick up a check and get her name on the credits. If you’re going just to see her, stay home. The new female player in this game is Noomi Rapace (who starred in the Swedish versions of “The Girl with the Dragon Tattoo.”

“Sherlock Holmes: A Game of Shadows” is a good, not great, holiday diversion.