I flew over the straight in March this year, flying out of Welly and looking across South island the scenery was uttely stunning, and you could watch the ferry making her progress up the Sound.
I'd done that crossing some years ago. I personally thought it was not too bad that day, but loads of other pax were bright green. One of the crew told me it was normal.
Coming back three weeks later saw terrible weather, so six of us chartered a Cessna Caravan and flew; very bouncy but only half an hour of terror coming into the Windy City. Other friends stayed with the ferry option, which was delayed six hours, and on arrival they were drained of all life and stomach contents... Oh my, how we laughed!