Grevious' coughing: OK, I get it that he's sick... But why? Why is he sick? Is that just an excuse for Obi Wan being able to defeat him when Ki Adi Mundi and Aayla Secura couldn't do so together?
The Lizzard: I don't have much of a problem with it, except that it was a much brighter green when it first appeared than it was later on. Toning down the color saturation should fix this.
Anakin's Turn: I agree that this was pretty weak, especially compared to his turn back to the light. If there was something that could make it take longer it would help. I don't see what more could be done.
Vader's Scream: I don't know. It is way OOC for Vader, but the scream itself is handled well enough. BUt it's still way OOC and shouldn't have been done. Editing out the scene would be best. Cut away after he asks where Padme is.