It is a fun game, lots of exploration, and certainly no where near as calm as endless ocean (there are hazardous animals everywhere, especially in later levels). Although besides the invisible barriers (which I have only encountered once), I have also had the game freeze outright on me twice and almost freeze another time. I had to force-reboot my wii in both instances.

Also, as a nitpick, there are no hazardous plants in the game. When you mention plants, you are probably thinking of either the purple spiky things, which are a type of animal called sea urchins and are relatives of star fish (and pretty closely related to us), or the swaying purple/blue and red/yellow things anchored to the walls, which are a type of animal called sea anemones and are relatives of jellyfish (which are also in the game). Then there are octopi and a bunch of true fish. But there aren't any hazardous plants, or much in the way of plants at all (there is a little bit of seaweed, but most of the backdrop is coral, also a relative of jellyfish and also an animal).