As it was late when I watched it in English, I only watched a few of the new scenes. However, it sounds like the same voice actors. Cloud and Tifa I know are the same. Zack is the same as Crisis Core. I don't think they got a new person for Marlene (which they did in Japanese), but Denzel sounded a bit different. Will have to rewatch when I'm more awake. ^^;

I don't think they redid Aerith's voice, either. Which is sad, but she didn't get any new lines, so that's probably why.