I loved fighting them in CE (i don't know but it felt like they were weaker in Halo 2), so much better than the Brutes, Elites were just amble, agile and very cunning and i loved fighting them but the brutes were mindless dumb apes and although they were overhauled in 3 extensively they weren't any fun to engage. After playing the Beta on invasion mode i love the movement and the animation for the elites, they look fantastic.
And yes on the Arbitter and Keith david, excellent choice.
One thing i don't think i can get use to straight off the bat for Reach is (although not a bad thing) that the Elites,Grunts and Brutes don't speak english now.