For their 50th feature-length cartoon, the Disney animators have returned to the genre that defined the studio: fairy-tale princesses. The nostalgia is a bit weird, though, since “Tangled” — based on the Rapunzel story — is computer-animated and in 3D. Visually, it’s “Snow White” meets “Shrek,” which is not a combination that’s liable to inspire a lot of wistful memories of one’s childhood.

The film itself isn’t particularly inspired, either, though it’s good enough not to embarrass ol’ Walt. It’s set in ye olden times, in a land where there are quaint cottages with thatched roofs, bawdy taverns where unsavory types gather, castles, towers, et cetera. Rapunzel (voice of Mandy Moore) is a golden-haired girl who was stolen from her royal parents when she was an infant. She has been raised by Mother Gothel (Donna Murphy), a vain old woman who uses the healing properties of Rapunzel’s magical hair to keep herself eternally young. If all of that so far sounds nothing like the Rapunzel fairy tale you’re familiar with, you may rest assured that this Rapunzel does indeed dwell alone in a tower and use her super-long tresses as a ladder for Mother Gothel to climb.

Along comes Flynn Ryder (Zachary Levi), a handsome rogue who has stolen a tiara from the king and queen. He stumbles upon Rapunzel’s tower while fleeing the royal guard and winds up being the sheltered girl’s escort out into the real world. Will Rapunzel learn that she is a princess? Will she discover an inner reserve of bravery and strength that she never knew she had? Will she and Flynn Ryder fall in love and live happily ever after?? I will not reveal the answer to any of these questions!

After a generic first act cobbled together from countless other fairy tales, “Tangled” finds its groove and starts to work as an affable tale of comedy, romance, and adventure. Nothing about it is what you’d call outstanding; as the 50th entry in a 70-year series, it’s overshadowed by films that have had more lovable heroines, more interesting heroes, scarier villains, funnier side characters, catchier songs, and more resonant stories. Everything it does has been done before, and better.

But there are still some fresh takes to be found. Mother Gothel, who looks like a cross between Cher and Julia Louis-Dreyfus might be a new kind of Disney villainess: the undermining, passive-aggressive, guilt-trip-inducing witch. She’s funny, but I can’t help but think she’d be more expressive (and funnier) if she were drawn with old-style cartoon eyes, rather than the large, oval-shaped ones that are the boring default on computer-animated characters.

Some of the best laughs are thanks to Maximus, a royal police horse with a no-nonsense attitude toward criminals like Flynn. Maximus belongs to the grand tradition of Disney creatures that are full of personality even though they don’t talk.

The songs, by Glenn Slater and Disney veteran Alan Menken, are serviceable but forgettable — save for “I’ve Got a Dream,” a rousing number sung by hook-handed thugs and old-timey gold prospectors. Touches like that remind you of the beloved Disney magic. It’s still alive, if not as spry as it used to be.

B- (1 hr., 32 min.; PG, mild action violence.)