It's funny, I beat The End the first time with level 35ish characters. Ok, it's useful to develop gifts with status-inflicting properties because The End was confused, sealed and put to sleep during the fight. Only had one traitor left (I thought there were only 2...)
So from what I read here, it doesn't seem worthwhile doing NG+ except for the trophies. Everything else can be Youtube'd, right?
Other than that, I did like the game.