Parents of girls will have no need of an introduction to the little mermaid, Ariel, a daughter of the king of the sea who yearns to become a human. She is also a Disney princess, and if mums and dads have had to watch the classic animation feature of 1989 umpteen times and buy the merch, they will know her story full well.

At least as we start out, she is no simpering captive in a tower, waiting to be rescued. She has one of the seven seas to watch over, and we like that. She is headstrong, in a Disney fashion, and restless to know and understand more beyond her underwater world. Another tick. Her curiosity above and below water has had a boost since the original film from directors Ron Clements and John Musker.

Objects from shipwrecks that have floated down to the ocean floor have spiked her interest and they are stored away in secret, contrary to her father's explicit commands. When King Triton (Javier Barden in resplendent beard) happens upon her den of treasured bric-a-brac like fob watches, broken statues, cutlery and telescopes, he lets his right royal temper rip, and destroys everything he can.

Bad temper seems to run in the family. Triton's estranged sister, the sea witch Ursula (the terrific comedienne Melissa McCarthy in bloated octopus form and scary eye makeup) films the screen. It's a rambunctious encore for her evil character who since the original film has secured a spot as one of Disney's best villainesses, though she has not quite eclipsed Cruella de Vil (One Hundred and One Dalmatians) on that score. Here she again fills the screen with clouds of ink and bitchy bile.

Ursula has been greatly embellished since the literary original written by Hans Christian Andersen nearly two centuries ago. The terror of sharks also gets a boost, in opening sequences where an apex predator chases Ariel through a shipwreck.

The winds, waves and rocks send Ariel another attractive and fascinating object from the world of humans. Aboard ship above her, handsome Prince Eric (Jonah Hauer-King) is a mixture of Prince Harry and Errol Flynn dangling from the rigging before his ship hits rocks during a storm. Ariel rescues him.

After taking Eric to safety, Ariel disappears before he knows her identity. As soon as he can, he begins to search for the only woman in the world for him, whom he will recognise by her beautiful singing voice. The mermaid is smitten too, doing a Faustian deal with wicked Ursula for a few days on land in human form - but mute. Ariel is engagingly played by young African-American singer-songwriter Halle Bailey.

Every now and then, Bailey's character takes on a life of her own, grabbing the reins from Eric, visiting a market and joining a dance party. But the weight of this overlong production is a drag on the impact of her spirited scenes, despite the legacy of the original soundtrack with additional numbers by Lin Manuel-Miranda (In the Heights, Hamilton, Moana and more) .

The sea world created here alternates between bright and sunny shallows where the stage is set for some signature tunes from Sebastian the crab (Daveed Diggs), like Under the Sea, and the murky depths where Ursula lives with her moray eels. Were we not given the prompt of floating hair around characters' faces, it might not seem watery at all - not compared with the gloriously rendered alternative natural world created in the recent Avatar sequel. Cinematographer Dion Beebe has, however, had notable success with this film's director Rob Marshall on productions with high visual impact like Chicago and Memoirs of a Geisha.

Generations of young women know The Little Mermaid story by heart. At least the tragedy of the protagonist is vastly different from what happens to her in the original fairytale, but what to make of the Hollywood ending here?

The director has apparently said his live-action, CGI-enhanced underwater musical is about Ariel finding her voice. That will be up for debate.

It's also worth noting that the latest Disney princess story is over two hours long and now rated PG, where it was once a much shorter, G-rated animation suitable for the entire family.