"Matilda the Musical," the London import that opened on Thursday night, is the most satisfying and subversive musical ever to come out of Britain...As directed by Matthew Warchus, with a bright, efficient book by Dennis Kelly and addictive songs by Tim Minchin, "Matilda" is as much an edge-of-the-seats nail biter as a season-finale episode of "Homeland."...Above all it's an exhilarating tale of empowerment, as told from the perspective of the most powerless group of all. I mean little children..."Matilda" captures the particular dread that runs like an icy rivulet through even the happiest childhoods...You just have to use your imagination and think everything through carefully, so it's all of a piece. That's what the creators of "Matilda" have done. Such strategy should be obvious. But in the current landscape of Broadway it's applied rarely enough to make this show feel truly revolutionary.