I think the voices are very well done and good quality. I like the narrator but it takes time to listen to him, it's nice they added a switch for separate channels. There are accents from different nationalities that match the character in the game, which doesn't surprise me because this game likes to caricature society.
A few generic lines (see ya, nice chatting, bye, ...) feel sometimes out of context, like an NPC very unhappy about you, who then says a jovial "hope to see you soon!" when you end the conversation. But I've seen that in other games. I think I noticed that here because each NPC has its own text conversation, but shares the same voiced hello / bye with some others.
I'm also glad not all dialogues are spoken. I find that it's just the right balance, to emphasize the important parts and so that it doesn't take too much time going through all the conversations.
I do hope that they add a switch for the same repeated announcements we hear in all buildings. I had to solve a puzzle while listening to 20 of those stupid messages and sometimes it gets on my nerves - the old Larian broken record syndrome. The same goes with TV sets repeating the same line every 20 seconds or so (some can be turned off).