Rubik's Revenge (4x4x4)
The Rubik's Revenge was the name given to the official 4x4x4 Rubik's cube. It is obviously a little more complicated than the standard 3x3x3 cube.
As with all of the other puzzles, the Rubik's own version is not very nice to turn. It also has a tendency to fall to pieces if you try to turn it too quickly and don't line the corners up well. There are more parts to a Revenge so it is a pain when you have to put them back together - when they pop, all of the pieces fall out. Eastsheen 4x4x4 cubes turn a lot better, are a little smaller and cost a little less. The puzzle in the picture is a tiled version, about the same size as the Rubik's revenge. It came from Puzl and turns quite nicely. The Eastsheen version, being a little smaller is just a tad more comfortable to work with.
There are two main approaches to solving larger cubes. Most speedcubers use what is called the reduction method. This means placing all of the centre pieces and pairing up all of the edges. That leaves you with a standard 3x3x3 solve to finish with. There are a few types of parity error that creep in because the centres are not marked. An alternative approach is to solve all of the ouside pieces (corners, then edges) and then laboriously place the centres at the end. This has the advantage of eliminating the parity errors and is altogether easier to understand and execute. Unfortunately, it is the slowest approach.