If you look back at a lot of TV programmes, film and games some earlier versions or the first episodes the acting is atrocious, or really low budget.
Either the actors become more comfortable, or simply improve.
The voice acting in;
SPOLIERS;
Final Coil of Bahamut story-line is fantastic.
Louisoix, Alisae and Alphinaud suited their parts perfectly, it didn't feel jarring, unbelievable or overacted.
Louisoix had that perfect deep husky voice that you'd expect, whilst the twins that refined, higher class up-bringing tone.
Still not as good as the voice-acting in 1.0 (but yet again, neither are some of the cut scenes)