I have been searching this client for a little while, and found that it's purpose is mostly for making multiplayer more interesting (the addition of RPG elements into the game along with some interesting mobs).
It is something to note, that the project is still in the Alpha-State, so perhaps it would cool to suggest some interesting ideas to put into the game (perhaps some village-quests, bosses, new powers, or even an ever-present force, like The Lord of the Rings's Isengard, positioned in the nether).
Until then, It would be best to create your own quests. For myself, I have:
[li]Create an Impenetrable fortress[/li]
[li]Discover Different Unique Items[/li]
[li]Try my hand at using the Skills on the Ender Dragon (or atleast ghasts)[/li]
*I am also looking for some sort of guide about the current elements in the client, so far without luck*