Enjoyment: This was really fun! The mechanics are simple, but it controls well, and it's very satisfying.
Concept: It's almost a strategy game, which I love. Kind of reminds me the cell stage in Spore.
Presentation: Minimalist, so there's not much to say here, but I like how well you communicate the idea of a frog with just a green circle, a pink line, and the movement system.
Use of the Limitation: I love how your perception of the level changes as you grow. As a tiny frogling, everything is one colour, and fish are sudden, capricious death. As you get bigger, you see the shape of the lily pads, and of the whole pond. The fish become something you can understand and avoid. Brilliant.