I swear this exact same post was posted just last week... anyway. I think mainly of the game, but disregarding that, I find Halo presumptuous - I feel the same way about similar names like
Angel and Heavenly, and I agree with LMS about it perhaps being too intense.
Plus, I prefer it on a boy than a girl, and I much prefer Helo (as in Battlestar Galactica's
Karl "Helo"
Agathon) over that.