I haven't played KH2, but I didn't think George Newbern's voice was that great for Sephiroth in FFVII AC and a few clips I saw of KH2. I think Lance Bass did a pretty good job with the lines he was given, despite the fact that so many people bash Sephiroth's voice just because of Lance Bass playing him. And why do people say Lance Bass had only 4 words or 4 lines as Sephiroth? Here's everything he says:

"Out of my way!" (Fire Pillar early in the battle)
"Time to die!" (Fire Pillar later in the battle)
"Come!" (before using Heartless Angel for the first time)
"Descend, Heartless Angel!" (it's not Sin Harvest!)
"Come, power!" (he starts using Omnislash)
"Prepare yourself!" (during Omnislash)
"No more games, show me what you've got!" (the last hit of Omnislash)
"No mercy, time to die!" (the last hit of Omnislash, alternative)
"I am the chosen one!" (he starts using the Meteor Storm)
"Come... to be one! I shall lead you to the Promised Land!" (during Meteor Storm)
"That was true power!" (after using Meteor Storm)
"Dodge this!" (last phase of the battle)
"Meet your fate!" (last phase of the battle)
"The Planet... it has failed me!!" (when he's defeated)

I don't know about you, but unless my calculations are totally wrong, that's way more than 4 words.