Halo: Legends was an ambitious project, but not a concept unproven. Following in the footsteps of Batman: Gotham Knight and the Animatrix, this compendium sought to expand upon the universe of the Halo video games. The question is, did it deliver?
From a strictly visual standpoint, yes, the films delivered, providing eye-catching anime graphics. Even in some of the more...conceptual episodes, like "The Duel", which was animated to look like an oil painting come to life, the visuals were engaging. The only exceptions to this rule would be the cheaply rendered "Homecoming" episode, featuring "Stylistic" animation cheats like stationary runners and rather stereotypical character design.
Sound effects wise, the shorts were solid, with fitting sound effects for weapons, vehicles, and creatures, as well as appropriate usage of Martin O'Donnell's soundtrack, excepting the final episode "The Package", in which the incidental music was largely passe, typical sci-fi music.
So where do these films fall short? The execution, plain and simple. The storylines are, putting it lightly, on writing par with episodes of Mighty Morphin Power Rangers. This works for non-canonical comedy episodes like "Odd One Out", where "Spartan 1337" is supposed to be a Large Ham. However, in nearly every other episode, this leads to the dialogue and plots coming across as a little...forced. The voice acting ranges from subpar (everyone in "Prototype") to hammy (Master Chief & Company in "The Package"), and it's actually not THAT jarring. Where the films really fall short is when they fail to convince you that this is Halo. The weapons, vehicles, and characters don't handle at all the way they do in the games. Granted, there are some times when exceptions must be made. (The Hrunting/Yggdrasil suit is obviously overpowered, and Spartan 1337 is a comedic character) The most egregious examples are largely found in "The Package", in which Spartans acrobatically leap through the air, somersaulting in slow motion, dual wield weapons that cannot be wielded in-game, energy swords deflect bullets, and all aliens have green blood.
Overall I'm giving the series a 6/10. It's fun and enjoyable the first time around, and there are some downright spectacular crowning moments of awesome. However, the storylines aren't interesting, and the dialogue is snicker-inducing.