Rode this on my bike in the annual Motatapu Bike event - holy cow what an epic journey! It would be an amazing walk as well (I think it is normally only open as a walk.....). The first part is pretty much up, then an undulating section that goes on for a while before the descent into Arrowtown. A few river crossings along the way, the most significant being at the Arrowtown end. Load up on water as I wouldn't recommend drinking from streams especially with the amount of stock cruising round. There is a river infected with Didymo along the trail so it is worth washing your boots after the trip so that other waterways aren't destroyed!