I have completed nearly everything in the Japanese version when it first came out, and I just got the English version a few weeks ago. For the most part, the voices are pretty good/okay. The characters that actuall sound better are Onion Knight and Terra. ESPECIALLY TERRA. And the ones that I really don't like are Squall, Cloud, Sephiroth, Zidane (I STILL SAY IT AS ZIH-DAYNE BUZZ OFF), and maybe Bartz. Squall sounds like such a douche I swear, and he breathes way too much during speech. Cloud because he's still that gross depressing kid that wasn't in the original FF7. I miss old FF7 Cloud. ;_; Almost everyone else is alright.
Oh, and I do not accept these so-called, CORRECT PRONUNCIATIONS for Tidus and Zidane. I've been pronouncing them as TYE-DUS and ZIH-DAYNE for way too many years to switch now. Besides, they sound better than this official nonsense.