Ok, just finished watching the first disc.
Visually, as beautiful as I remember, and incredibly clear. The wonderful detailing and lush backgrounds and colors were always one of my favorite things about the show. The sound actually wasn't as bad as I remember; it probably only got repetitive towards the middle. At the beginning it works quite well.
Trivia: Apparently the plural of "yoma" is "yomi". Or at least that's the label for the extras section where they have a handful of the voice auditions. Nothing particularly amazing, but a cute bit in Rubel's clip.
Script: There were several places where a bit of rewriting was done that seemed inappropriate. The most blatant that I remember was Clare telling Raki about Claymores not aging during their little talk in the desert where she originally was just describing a bit about when she became a Claymore (and dodging the question).
Another is when, at the end of the first episode, Clare asks Raki if his village threw him out. In the Japanese he says "No." In English he says "Of course.", and the dialog of the flashback is more blatant about pushing the fact that the village did indeed throw him out. In this case, despite it shifting Raki's attitude slightly, it was nice not to have to figure out whether he actually meant what he said. That particular scene really bugged me in the manga, and somewhat in the anime, because I was never quite sure whether he was just being stubborn about denying the events, or he really did mean what he said and that he actually ran off on his own.
For people who have studied the source religiously and have as many debates about things as we do on this forum, the rewrites stand out as big greasy thumbprints. For someone not as familiar, it will be barely noticeable. The question is about how much it changes the characters. For the most part, almost none. The one I'm least certain on at the moment is Teresa.
For the dub voices:
Clare - Very good. While there are a number of moments where her voice seems to 'stumble' a bit against the character, for the most part she held Clare's emotional wall quite well. The bits that grabbed my attention the most (in a bad way) were also the bits where it felt like they were trying to rewrite the story flow a bit. When she can just have the character to herself and run with it as in the original story, she does great.
Raki - I'm sure you'll be happy to know that he's as annoying as ever.
Actually, given the character, the voice seems to fit quite well, and I have no problems with the dub of it (abstracted away from the character itself). One nice thing is that they did some good rewrites of his speech so that he wasn't always mindlessly repeating whatever someone just said ("half human, half yoma"... "brains....") As opposed to Clare, I think his voice came out better due to the rewrites.
Zaki and the Impersonator Yoma - Both had good voices, and they did some interesting things with the vocal mixes for the monster effects. The impersonator was done as a female; every time I listen to the Japanese I can't quite decide whether it sounds like a deep female voice or a moderate male voice.
From the commentary, apparently they tried to put together a number of unique variations on how the voices were done throughout the show to give the various yoma and awakened beings their own distinctive flavor, as opposed to just generic pitch shifts. I'll be interested in hearing what they did with Priscilla, who should be on the next disc.
Elena - Not much to say. A competent performance.
Rubel - Absolute dead on. A creepy, vaguely wheezy, edging towards Emperor (Star Wars) voice without sounding old and frail. Cute bit from the voice audition for his voice where he said, "The Emperor is not as forgiving as I am."
Galk & Cid - Solid. While I wouldn't go quite so far as to say perfect, they both did a very good job, and I have no complaints.
Father Vincent - Quite good. Honestly, a lot less to go by than I remembered, but he still sounded good.
Teresa - The biggie. This is the one I'm having the hardest time on. The rewrites for her made her far more serious. Rather than the whimsical wondering if she'd be able to find the 7th yoma in the town, it's more of an "Oh. There you are." Her treatment of Clare seems more antagonistic than merely annoyed.
There's a general deep tone to her voice that makes it so that I just can't hear the "Faint Smile" appelation come through. There's less of the feel of "I'm so good I can play games just to amuse myself", and more of the dead-serious vibe of the Terminator saying "Come with me if you want to live."
Despite the complaints, it's not actually a bad job, just a somewhat different take on the character. The voice acting itself is excellent, and really stands out in the brief moments in this episode where her mood lightens slightly.
Orsay - Teresa's handler. Not as dead-on as Rubel, but decent enough.
Miscellaneous dudes - General riff-raff, so nothing special, but notably none that scream "amateur!" One thing that grates on me to no end is having a wonderful dub interspersed by awful instances of "Villager C".
Extras, Commentary track: generally boring patting-each-other-on-the-back stuff. A couple interesting points, but not particularly worth the time.