While I can agree with the her japanese seiyuu being th obvious better in this scenario, i'd still like to see how Willa can handle the more emotional scenes as the game progresses. As Sky said they sound great in battle, but Aqua/Willa Holland actually sounds like she's in battle. When Terra says "WANT SOME?" it just sounds very off from his normal voice of what we've seen.It it still not as bad as aqua's. Terra's I can live with but not aqua. I really think I could do a better than her.
The only voice i've truly ever hated in Kingdom hearts was Alyson Stoner as Kairi/Xion, and to this day I still can't get used to her.