I know nothing of this cough yet (avoiding spoilers for the most part), but it definitely sounds kinda lame.
I don't care for him at all, I think it was stupid to create this extra character when Dooku could have filled the same role. The coughing thing is annoying as well
I've hated the Grievous character since it's inception really, but after seeing some of his footage at C3, I have to admit that he's looking a lot cooler now, and I'm actually a little excited to see him in action.
But one spoiler I recently ran across somewhere said that there were FIVE lightsaber battles in ROTS. I already know of most of them:
Anakin & Obi-Wan vs. Dooku
Mace and Jedi vs. Palpy
Yoda vs. Sidious
Anakin vs. Obi-Wan
and presumably Obi-Wan vs. Grievous (I know they fight, at least)
But what bums me out a bit (especially after watching the CW series) is that Grievous apparently takes no part in the killing of any of the other Jedi in ROTS? I always figured he must play a large roll in the Jedi massacre, but it's looking more like that's just Anakin and the Clones.
Of course, like I said, I've been avoiding most spoilers, so I could be way off here...