SPOILER WARNING
The campaing of Halo 2, so far doesn't seem as focused as that of Halo, as you switch between Master Chief and Covanent persprctives. It is all a matter of personal taste, though, because some people find mixing the perspectives cool. But I would rather play as Master Chief than the 'Arbiter' any day. Also, I have as of yet to encounter any Floodies, which created some of the most intense moments of the first game. I really hope they show up later.
END SPOILER