-- The books do a terrible job of explaining it, but I think people are giving Halsey a hell of a free ride.
-- She kidnapped a bunch of kids, outright brainwashes them, replaces the kidnapped kids with faulty clones, forces them into military slavery the likes of which even a Janissary would go "hey dude that's a bit messed up", and for what: to be used as death squads against human freedom fighters. Think about that for a second. It's just lucky for their PR that the Covenant showed up or Master Chief would be chest-deep in human blood against those that had the temerity to go against the Earth colonial government and quasi-military dictatorship of the UNSC.
That's true, or at least it would be in a realistic setting, but this IS a universe in which humanity's destruction by its own hand was a mathematical certainty, foretold by the galaxy's greatest genius (with a magical destiny, or "curiosity", imprinted on her by an ancient alien), and by an AI shadow government that secretly guided our fates from the confines of its virtual masonic lodge. The more layers they add to the "fate"/"destiny" angle, the more it justifies Halsey's actions. At absolute worst, she would have ensured humanity's survival, at least until the Covenant's inevitable release of the Flood. Instead, she saved the entire galaxy. Oops.
From the perspective of a character in the universe, it certainly makes sense to demonize Halsey, but since we know the big picture, these stories become rather pointless and frustrating because the drama has to come from characters unaware of the kind of world they live in.
This isn't a Dune, where the creation of a Space Messiah would have its drawbacks, this is a comic book character origin story and Haley's project will keep paying off until the franchise and/or universe collapses.