Ahh, the life of a newlywed vampire.

No need to sleep, eat or use the bathroom. All the time in the world to canoodle with your eternal love in a fairy-tale cottage in the woods.

So you’d think Bella (Kristen Stewart) could muster a bit more enthusiasm — maybe a broader smile or occasional giggle over her bliss with vampire hubby Edward Cullen (Robert Pattinson).

Yes, Stewart continues to play her role too low-key, and here and there she narrates in a bland monotone. But overall, “The Twilight Saga: Breaking Dawn — Part 2” brings on the over-the-top thrills, especially in a climactic battle scene, glimpsed in the film’s trailers, that’s the rare instance of a movie improving on a book.

And, thank goodness, director Bill Condon wisely jettisoned the silly telepathic talking wolves from Part 1 and simply let them growl and menace. After all, we yearn to believe in author/producer Stephenie Meyer’s fantasy world.

Condon split Meyer’s fourth and final “Twilight” book into two parts. The new film begins right where Part 1 left off last year, when Bella has just opened her bright red eyes into the new world of vampire life.

As in the book, Bella immediately checks out her newfound powers, leaping effortlessly over a waterfall, running through the dense forest at lightning speed, scaling a sheer rock wall like Spider-Man in the gorgeous Pacific Northwest. At least Pattinson manages to look pleased.

As a “newborn,” Bella is temporarily stronger than the strongest vampire, and Stewart finally shows us the sheer joy of it all when she accepts the challenge to arm wrestle Edward’s big brother, Emmett (Kellan Lutz).

Meanwhile, last we saw Jacob Black (Taylor Lautner), he was forgetting all about his unrequited love for Bella and doing some seriously surreal bonding with Renesmee, Bella and Edward’s honeymoon baby. This “imprinting” that comes with being one of Meyer’s werewolves is the most bizarre part of the book, and the author takes great pains to assure us that this love is pure, like a brother-sister thing for now, not just plain wrong.

Lautner, buff as ever, pulls it off, appearing as a doting protector. If nothing else, it’s uncanny how 12-year-old Mackenzie Foy really looks as if she could be Stewart and Pattinson’s daughter, or a kid sister.

Soon, wouldn’t you know, there’s trouble in paradise. First come worries about Renesmee. Half vampire, half human, she is maturing at an alarming rate. If this keeps up, how long can she live? Will she be an old woman by the time she can drive?

(The special effects crew did an admirable job digitally “Benjamin Buttoning” the young actress’s face onto various bodies as Renesmee grows from little baby to toddler to young girl.)

And then there’s the Cullens’ vampire “friend” Irina (Maggie Grace, fresh from another kidnapping in “Taken 2”). She is about to pop in from Alaska for a visit and, viewing Renesmee from a far-off ridge, assumes the worst: that the Cullens sank their teeth into a human child and created an out-of-control immortal brat, verboten among vampires.

Irina rushes off to rat them out to the Volturi, the long arm of vampire law. These black-robed Italian overlords (led by a villainously gleeful Michael Sheen) are only too happy to come administer their punishment: death to all Cullens. And their werewolf friends, too.

Edward’s family enlists vampire allies from around the world. The Cullens need all the help they can get against the Volturi guard, especially Jane (Dakota Fanning), who can torture with just a stern look, and Alec (Cameron Bright), who can cut off all senses, leaving his victims helpless in the dark.

The movie takes on an “Avengers, assemble!” vibe, with superpowered vampires combining their forces: an Alaskan who can supply quite the electric shock, an Amazonian who creates powerful illusions, an Egyptian who can control the elements — giant waves, fireballs, that sort of thing.

And, if she can get her act together, Bella the newbie might have some tricks up her sleeve, too.

Not to reveal too much, but let’s just say that the book’s anticlimactic ending gets a violent twist. While the vampires of David Slade’s “Twilight: Eclipse” shattered delicately like porcelain dolls when they died, these vampires get their heads ripped off. That’s reportedly the reason the movie was almost slapped with an R rating. At least vampires don’t bleed.

The changes make for a visceral, satisfying climax. After the ups and downs of previous “Twilight” films, it’s good to have the series quit while it’s ahead.