CharacterController2D is similar to the built-in Unity CharacterController component. It has a similar API (mainly a move method that takes a delta movement) and is a really good base to make a super solid controller using Unity's new 2D goodies.
A simple demo scene is included along with a few Spelunky sprites (which obviously should not be used in your game!). An overview video showing how to get started is available on the prime31studios YouTube channel here.
The included demo scene is a minimal example to keep things simple. It has very basic input detection (using the arrow keys) and a simple character sprite/Animator setup.
Setup is pretty simple: drag the CharacterController2D onto your player/enemy GameObject and set the platformMask in the inspector to contain any layers that you want the player to collide with. If you will be using one way platforms, you can set the oneWayPlatformMask as well. Note that one way platforms should be EdgeCollider2Ds.
From there you can tweak the totalHorizontalRays and totalVerticalRays to your liking. When in the editor rays will be drawn with Debug.DrawRay so that you can make sure the ray resolution is appropriate for your smallest platform size. To turn off ray debugging just comment out the #define DEBUG line at the top of the CharacterController2D.cs file.
To move the player around just call move and provide it a delta movement. You can subscribe to the onControllerCollidedEvent to be notified of all collisions if you need them.
Attribution-NonCommercial-ShareAlike 3.0 Unported with simple explanation. You are free to use the CharacterController2D in any and all games that you make. You cannot sell the CharacterController2D directly or as part of a larger game asset.