Grievous seemed more menacing and interesting when I was just reading him in the RotS novelisation.
Then I went to the actual movie, and could have died of embarrassment at what I was seeing. It took a lot of rationalising to make me think that any of that was okay, and that didn't last more than a few months before how rubbishy it was completely sunk in.
The Matthew Wood thing is just the icing on the cake.