This puzzle was invented by Panagiotis Verdes and mass produced by the company Verdes Innovations SA. It is a WCA puzzle. I don't have one, but I know that to solve it, one must first match the center peices (16 on each side) and then match the edges. Solve like a 3 by 3 from there. Like the 4 by 4 and unlike the 5 by 5, this puzzle has no fixed centers and they must be oriented. There is a more detailed description and solution in the link below.
6 by 6 Solution