How strong is the coffee? How is it prepared?
It's the strongest stuff I've ever had. (And I drink Turkish coffee over here from time to time.) It's also delicious.
On my first trip to Argentina, they served yerba matte in the morning and had these little demitasse cups. I said "To hell with that," and poured mine into a regular coffee cup.
Right before an all-day meeting.
I was kicking the table legs, shifting in my seat and had a huge desire to climb the walls in the conference room.
I never made that mistake again.
Yerba Mate is a tea (leaves from a plant related to holly) and is prepared by adding just-under boiling water to it in a gourd, then sipping it through a silver straw (bombilla) with a kind of strainer at the end.
It's *real* strong and is an acquired taste.

This has some mate tea in it and is pretty darn good/is made like regular tea.
You can definitely buy yerba stateside, even online.