The mod adds useful features to Minecraft that can be used both in PVP and in regular survival.
The mod consists of two groups: (1) a fully customizable GUI interface system which consists of various, also customizable, interfaces such as a minimap, armour status, potion status etc and (2) useful key bindings that can make your gameplay more efficient, biggest of which is an rpg-like actionbar system. This mod is mostly client-sided. Installing it on the server side is optional for some additional features like world identification.
This is the first Minecraft mod I have ever released!
For a more complete list of features and some answers to frequently asked questions, please refer to the mod's PlanetMinecraft page.
If you're having trouble installing any of the mods, then some of the guides might help.