I actually think that the Japanese voices are a little too subtle. Light doesn't seem to portray enough megalomania, IMHO. L is close enough to the original, and each version of Ryuk has their own charm. I think Ryuk's Japanese voice actor actually is at his best in the Death Note live-action movies. One wonders if they got him to do a live performance like Andy Serkis as Gollum before substituting him with the CG Ryuk. He is trained as a Kabuki actor.
I am yet to see much of Misa Amane, but I think that any annoyance about her voice is more of the fault of the original characterisation of Misa in the manga, than anyone else's fault. In other words, Tsugumi Ohba wrote her that way, and you can blame him/her. Even so, it makes an interesting sense to have the second Kira this vivacious kind of girl, more positive and impulsive, compared to the more dark and brooding Light.
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(No longer a mod)
On sabbatical...