EZSprite is a really good package for those trying to cut through the fat and just make a 2d game.
Overall this package has a very easy entry point and a great sample that comes with it. It only takes a few moments to setup a character to animate. The animations work very similar to the normal animations GUI that models have.
Of all the assets and scripts in the package the most useful thing over all is the single sided mesh that is provided with the project. Its used in normally by the 2d sprites, but its very useful for whatever you need, like a platform that only has collision on the top.
The only issue in the system is the atlas generator, it uses a built in function unity has to compact a list of images into one image. This is completely random order however and results in an unusable image sheet.