I'm surprised at the comments from posters stating that Jane Powell made the same type of films Deanna Durbin did. Although they were both young sopranos whose film images were crafted by Joe Pasternak, if this film is any indication, they were almost polar opposites.
While, in THREE SMART GIRLS, Durbin plays an impulsive "Little Miss Fixit," who, after some setbacks, manages to reunite her divorced parents, in its' semi-remake, THREE DARING DAUGHTERS, Jane Powell almost destroys the marriage between her screen Mom Jeanette MacDonald and new stepfather Jose Iturbi when she refuses to accept him and strong arms her younger siblings into rejecting him, too. From the Durbin and Powell films I've seen, I'd say these disparate qualities permeate the early films of both of these talented young performers.
As for Durbin's performance in THREE SMART GIRLS, I find it completely winning, and most impressive. Although it's clear from her occasionally shrill and over-emphatic line readings in some of the more energetic scenes that this is an early film for Deanna, watching the self-confident, knowing and naturally effervescent manner in which she delivers her lines and performs overall, and the subdued and tender manner she projects the more serious scenes, you'd never guess that this was the FIRST film role of a 14 year-old girl whose prior professional experience consisted almost exclusively of two years of vocal instruction.
Given that this film, and Durbin herself, were much publicized at the time as "Universal's last chance," the production must have been an impossibly stressful situation for a film novice of any age, but you'd never know it from the ease and assurance Durbin displays on screen. Although she's clearly still developing her acting style and demeanor before the camera (this was equally true of the early performances of much more experienced contemporaries like Garland, Rooney, O'Connor and Jane Powell), Durbin projects an extraordinary presence and warmth on camera that is absolutely unique to her, and, even here, in her first film, she manages to remain immensely likable despite the often quick-tempered impulsiveness of her character, and though she's occasionally shrill, she never for a second projects the coy and arch qualities that afflicted many child stars, including Jane Powell and some of the other young sopranos who followed in the wake of her success.
In short, like all great singing stars, Durbin was much more than just a "beautiful voice." On the other hand, while Durbin's pure lyric soprano is a truly remarkable and glorious instrument, the most remarkable thing about it, to me, was the way she is able to project her songs, without the slightest bit of affectation or "grandnes" that afflict the singing of adult opera singers like Lily Pons, Grace Moore and Jeanette MacDonald in films of the period
The film is also delightful, heavily influenced by screwball comedy, it backs Durbin up with a creme-de-la-creme of first-class screwball pros such as Charles Winninger, Binnie Barnes, Alice Brady, Ray Milland and Mischa Auer. The story is light and entertaining. True, it's hardly "realistic," but why would anyone expect it to be? If you want :"realistic" rent THE GRAPES OF WRATH or TRIUMPH OF THE WILL. On the other hand, if you're looking for a genuine, sweet, funny and entertaining family comedy with a wonderfully, charismatic and gifted adolescent "lead," and terrific supporting players, this film won't let you down.

Perhaps I'm out of date or just don't know what Electra is like in current publications... But the Electra that I read was far more manipulative and always seems to have a plan. She usually used others to do her dirty work and more often than not some sort of double cross was involved. Just when you think you have it all figured out she pull the wool over your eyes and gets her way.
This movie was fairly weak on the dialog, the acting wasn't particularly convincing, and the action was spotty. I was really looking for something more along the lines of Frank Miller's book "Electra Assassin." Which is much darker than anything in this movie.
Special effect where cool, action was interesting at times, but more often than not the story and plot was slow or illogical. Tha Hand was not menacing enough, and Electra was not..... bitchy enough. She's the girl you love to hate... but in this story, I just didn't care either way.