Ditto it wasn't just run'n'gun the arbiter introduced a sneak mechanic which on harder difficulty levels made him that much more fun to play, especially on the level where you start off on a cliff top and can sneak past the brutes by getting above them, it felt like playing the Predator, a faster, leaner, meaner predator.
In Halo 3 when he finally kills Truth, that's a beautiful moment.
While the Chief just stands there like the faceless lump of metal he is.