The entire script sounds like it was read by actors who had no idea what the story was or who their characters were, or rather who they were supposed to be interacting with, and as a result the voice acting is really inconsistent and in some cases just bad. Zelda's voice in particular was a mistake, the actress evidently did not know what kind of emotion she was supposed to invoke as there was none at all in the performance, but I also found myself really disliking Mipha's voice. It was just too "I love you Link but I'm depressed and what is life" for my liking, although her character was the exact same way (fite me, Mipha's character sucks and I stand firm with that opinion) so it fits I guess.
That being said though, I really liked Revali and Urbosa's voices. While there were still some moments that give the thought of "do they actually know who they're supposed to be interacting with?", these two characters definitely had the strongest voice acting in the game.
Overall, not a big fan, but I appreciate Nintendo for at least trying. And, to their credit, they've never really had a lot of success with voice acting in their games (Super Mario Sunshine, I'm looking your direction) so they at least had the guts to try with one of their most ambitious games yet.