Here's where a blatant disregard of a number of rules works exceptionally well!
Rule of thirds? Nope—the nearly perfectly centered dark eye of this little frog IS the focal point. Combine this with the shallow depth of field and the soft leading lines of the leaf on the left of the frame, with the definitive edge of the leaf leading in from top right and you've got a soft, yet dynamic composition that a powerful image that's easy to read.
One might argue that the palette is a bit flat, but this is a whispering image, so there's no reason to crank up the contrast to shout at the viewer. In fact, boosting contrast takes away from the feel of this moment.
Throw in the asymmetrical tone-on-tone balance of the right section of the frame where the leaf edge ends, and you've got a winning shot all around, elegant, simple, and beautiful.
Online Technology Editor