Thanks for the feedback! There are some choices at the beginning in the prison (do the players try to escape and help other inmates or not?) and in the end, that makes it interesting to see what the players will do.
My tip for DMing this adventure is to skip time and move on to the next day if the SCs feel like there is nothing more to do. Nevertheless, encourage the SCs to test an unusual kind of freedom: death is not permanent; they come back after one day. Just like in the movie: Edge of Tomorrow. However, my players had too much fear to test that more than once!