The Gear Cube is an invention of Oskar van Deventer, who is responsible for a number of other puzzles, some of them twisty puzzles. The gear cube has the same number of pieces as a Rubik's cube, laid out in the same way. The difference is that the edge pieces are cogs. When you turn a face, the adjacent slice is turned half of the angle that you turn. When you turn a face through 180°, you also turn the adjacent slice through 90°.
The gear cube is a very interesting idea and the puzzle is very well produced. Despite the initial confusion about the effects of the turns, the puzzle is pretty easy to solve.