For me it was really hard to navigate around the starfish and the spikes growing on the sides. Too fast and I can't navigate around them in time, too slow and I can't move out of the star fish fast enough. Some areas I had to just repeatedly die and rush through before the enemies respawned. The controls do make me feel like I'm controlling a fish and would be great for other types of environments, but requiring tight-ish movement in narrow passages makes it hard to use.
Hope that helped some.