So I was just reading the Dungeoneering guide and can someone just summarize to me what it is? What are some common benefits from this? Any cons?

You mean the skill in general?

 

Assuming that, essentially you are attempting to complete floors as fast as possible while maximizing completion in order to gain the most experience. Various methods exist, its best to partner with somebody to learn. The skill itself contains few benefits outside of Damonheim early on; however, resource dungeons often prove convenient/uncrowded/lucrative, the various scrolls often improve efficiency, and, of course, the chaotic weapons are quite often the be all, end all for weapon choices.

 

As for cons, I think the only issues with the skill is it can be somewhat confusing at first, people can be (wagon)holes to you if you get a bad team, and its terribly addicting.

 

Well worth training, and very fun overall.