Yeah, not "bad" in a traditional sense, but for a company that prides themselves on not releasing a game until it's ready, WW for me, was not ready. And the whole time I played it, I thought how little was actually done, and how much they just made the game long with "treasure hunting" in a HUGE open sea. I don't consider that great game design, but short cuts which I was charged full price for. So for me, that's about as "bad" as it gets.
None of that bothers me.
GameCube was a weird time for them, as Super Mario Sunshine was also rushed and was an unmitigated disaster of a game. It controls poorly and is overly complicated as the next Mario game after Super Mario 64. A Hat in Time really shows what that style of 3D platformer could be if it was done well.