I'm only in Chpater 17 right now, and I haven't noticed any plot holes yet.
The VO is absolutely excellent. Don't believe everything the haters say.
The only one of the voice actors who is good-ish is Madison, for whatever reason the developer didn't want to get professional voice actors and it shows. "Jason!" "JASON!"
As for the plot holes, TVtropes has a nice big list of them, for when you finish the game.
What do you expect? Ethan is just a normal family guy, not some Patrick Stewart. Madison otoh sounds more like your average chick.
I best liked the VO's of Scott Shelby and Norman Jayden. Norman the smart and gentle guy, and Scott the scruffy and somewhat tired guy. They nailed their characteristics completely.