Legendary Solo wasn't too difficult to be honest. Then again, I'm a total Halo nut
on XBL as well, maybe we can play some campaign later today.
I have only played Halo games on co-op, they seem boring to play on your own.
Well, I enjoy the story (yes, I've read all the novels), also:
They aren't challenging at all in co-op, the only (albeit mild) challenge is Legendary Solo (although to be fair, Legendary Solo in Halo 2 was kind of a pain).