2D vs 3D Programming

[davidthefat]

Im assuming that they are about the same level of difficulty for programming right? Im 3D, you just have one more axis of coordinate to worry about. In 2D, you still need to control the camera, collision and stuff, just all in 2 dimensions. Its just that in 3D, you have to worry more about how much memory and if its executing fast enough like the frame rate and the loading part. Is there more than that in 3D programming?

[Spikey]

In general its the same thing, but with an extra axis like you say, although that does makes things a little more complicated.
Theres some more things you may have to do, like calculating normals, optimize culling, fixing zdepth and blending issues, gimble lock problems, quaternions, loading and animating models, mipmapping, skyboxes, terrains. That's all I can think of right now.
Then there's the whole time cost of making the 3D content instead of just 2D, although thats more an artist thing than programmer.

[rolland]

You'd probably also have to learn another whole API. (OpenGL, D3D, etc...)

[davidthefat]

You'd probably also have to learn another whole API. (OpenGL, D3D, etc...)

Obviously... OpenGL supports both 2d and 3d