I'll respectfully disagree. No matter where the story is, the villain - in stories like these, mind you - is always better as a subtle, quiet, reserved and almost shy type, not a flaraboyant, outgoing, over-the top energetic and happy one. It then makes it more sinister knowing that while he's so quiet around everybody else, there's then the side of him we see that no one else does. If he's all happy-happy joy-joy around everyone else, it'll just grate on everyone's nerves and will make it less shocking - meaning it's more predictable. I mean hell, even in the Japanese Light was a subtle type, not outgoing and energetic; why would that not just the same lend itself to this?
Likewise, look at Mikami, who is in some ways Light version 2.0. Outwardly, he's a quiet, mild-mannered prosecutor, and a methodical man who never once acts all over the top happy - he rarely even smiles in public, and if he does, it's just this faint smirk that implies nothing to anyone but the audience. Would you ever expect THAT to be a mass murderer? If so, you can see why it's better to keep the actor quiet, and not have him be the musical type.
Hell, even the somewhat similar character of Ken Ichijouji was subtle. If it weren't for how blatantly obvious the writers made it that he was the Kaiser, would you suspect that?
In short, I think the writers for this will have a better movie on their hanRAB - and I'll approve of this more - if they find a more reserved actor for the role.
And another actor I might suggest for L: Taylor Kitsch. Hey, he played Garabit well in Wolverine (and what's funny is guess who Alessandro Juliani, who voices L in English, also played?)
Also, I know I keep saying this but - BRING BACK DRUMMOND AND WHEELER FOR REM AND RYUK!!! HEY IT WORKED TO BRING PETER CULLEN BACK FOR THE TRANSFORMERS MOVIE AND GUESS WHERE HE'S FROM?!