When trying to find what doesn't work in Ninette many things come to my mind. They are not the predictable ones though: The unusual scenarios (all interiors!) or the choice of an actress like Elsa Pataky (imitating a French accent) work incredibly well, and the start is the best part of the movie. As the movie goes on the only flaws are probably the hyper-naive script where characters seem very artificial and implausible, especially Carlos Hipolito who disappoints a little whereas Pataky does a quite a goo job. I haven't read Mihura's works and I suppose they worked well in theatres but it don't translate very well to cinema. The way Ninette acts, the parent's ideology's caricature and the protagonist's friend (the kind of gags) are the things I reckon less attractive of this film.
But the film doesn't crash until the family moves to Murcia and an absurd and unnecessary part is added to the film. Well, I know that everything is Mihura's two work's adaptation but it doesn't justify what starts there. They appear in Murcia (where no one has a Murcian accent and they are even laistas) and the protagonist has an attempt of affair with Mar Regueras (who wouldn't, being married to Elsa Pataky) but it doesn't go on, ending with a sudden and strange outcome. The last part back in Paris is even more strange and confusing.
So I found the first part in Paris acceptable and the rest just awful. The film seems to rely on Pataky's body to succeed and that's why they released it in august, I suppose.