It's important to keep in mind that Emoji Keyboard won't work unless you already have GO Keyboard installed. So the first step is to install GO Keyboard and then, and only then, Emoji Keyboard.
Once you have Emoji Keyboard installed and set up, you can start using its more than 800 emoji in any text field. In addition to the normal icons, you'll also find hundreds of smileys that can be pasted into a text field by simply clicking on them.
Emoji Keyboard is a unique custom keyboard and while it doesn't have interesting options or keyboard shortcuts, it does let you paste hundreds of emoji into conversations at lightning speed. In other words, as an additional keyboard, it could be very useful.
Requires Android 2.0 or higher