I don't see any bugs here. Pathfinding is pathfinding and it's designed to find the shortest path, that is, the path that consumes the least amount of TU. I like the current behavior and, in fact, I would consider it a bug if a unit didn't take the shortest path. The zig-zag situation that Ethereal experienced, I also experience all the time, except I WANT the unit to take the zig-zag route because it saves TU. When I see grass or other slow terrain on the floor, I know that walking on it consumes more TU, so I expect the pathfinding to find a wavy path through it. If the path bothers me, I can always move the unit 1 by 1 tile, but 99% of the time I prefer the shortest path.