Rooney Mara and Daniel Craig star in “The Girl With the Dragon Tattoo.” (Merrick Morton/MERRICK MORTON)

The Girl With the Dragon Tattoo” finally opens in theaters today, allowing fans of the Stieg Larsson best-seller on which it is based to get some important questions answered.

Is David Fincher’s adaptation a good film? Yes, it is, although purists may quibble over some modifications to the narrative and the way the romance between Mikael (Daniel Craig) and Lisbeth (Rooney Mara) develops. (Reviews so far have been slightly mixed, but mostly positive. The Post’s Ann Hornaday calls it “at once satisfying and underwhelming, a pristine, coolly atmospheric procedural thriller that comes to the party a tad overdressed in inexplicably breathless hype.”)

Does Rooney Mara make a convincing Lisbeth Salander? She does, albeit an arguably more inscrutable and slightly more vulnerable one that Noomi Rapace did in the Swedish version that preceded this one. (Or as vulnerable as one can be when she’s willing to enact diabolical revenge on an abuser.)

And then there’s this question: did Fincher need to make this film at all when that perfectly fine Swedish subtitled version was released in the U.S. just two years ago?

“Need” may be a strong word in this context. It was inevitable that Hollywood would eventually try to tackle the Millennium trilogy for one basic and obvious reason: money. Larsson’s books stand as one of the most successful publishing phenomena of this, well, millennium so far. Millions of people have read these stories. That provides enough brand recognition and built-in curiosity for a studio like Sony to build upon.

Also, as silly as it might sound, there are still lots of Americans who will not go to see a film if it has subtitles; reading during a movie is too much of a distraction for them.

But apart from box office dollars, what is there to be gained from redoing a film that so recently made its mark and launched the career of Rapace (who, for the record, is competing against “Tattoo” this season as one of the stars of “Sherlock Holmes: Games of Shadows”)?

This debate was raised last year when the remake of another Swedish film, the adolescent vampire thriller “Let the Right One In,” was released in the form of Matt Reeves’s “Let Me In.” I liked both films, but must admit that Reeves’s underrated version ultimately stuck with me more because he added a specific twist on a main character’s backstory that wasn’t in the original. It added a whole other layer to the narrative for me, and one that made it that much more haunting.

I am not sure I can say the same for the pair of “Dragon Tattoos.”

I would argue that both “Tattoo” movies stand on their own as solid, well-executed films. Both feature strong performances by their Lisbeths, appropriately chilly atmospheres and brutal violence that absolutely merits their R-ratings. The Fincher take incorporates more of the story involving Wennerstrom, the billionaire Blomkvist is accused of libeling. The first one, directed by Niels Arden Oplev, provides a bit more useful information about Lisbeth’s background.

But if someone asked me to recommend one versus the other, I might give a different answer depending on which day I am asked. There is no “Let Me In” gamechanger moment for me that tips the scales in one direction or another.

And maybe that’s a reflection of the aforementioned chilliness. While the “Dragon Tattoo” movies are indeed compelling and suspenseful — I believe critics are contractually obligated to refer to both by using the word “taut” — neither one had a lasting emotional impact on me. Perhaps it’s all those slick, icy patches on the Vangers’ Hedeby Island estate, or just the general frigidness of the proceedings. Whatever the reason, at least after part one of this three-part saga, I am interested in these characters more than I actually like them.

The bottom line is that both “Dragon Tattoos” movies are riveting to watch. But neither is likely to make audience members feel anything terribly deeply when they leave the theater and walk out into their own chilly, dark nights.