Yes, I have had it now for about 2 yrs. A friend sent it to me
for Xmas, and I found that it totally fixed my gall bladder problem (for now). I've had lots of tests, scans showing nothing but I get episodes of pain/gas from it.
Surprisingly the Yerba fixed it. I only use green unsmoked type. It is made by EcoTeas which I buy online in bag form.
I found an extract in capsule form, also, which I use if I am not in the mood for tea. It is called Green Mate, by Jarrow.
It works just as well!
http://www.iherb.com/ProductDetails.aspx?c=1&pid=194

I found PubMed papers about Yerba Mate being a chloeretic which explains the GI improvements with it.

If you decide to use it... only buy the green type, the smoked is implicated in oral cancers...due to the smoking etc. (like other smoked foods etc). People in S.America drink this avidly...consuming huge amounts daily...I only do one tea bag or one capsule daily. That seems plenty for me.
Don't heat the water really hot, because that destroys the antioxidant and other nutrient benefits. (no boiling etc).
EcoTeas have a nice website...you can Google that easily.
Yerba Mate has been tested and found to have twice the antioxidant content compared to green tea!

I really like it, and it has been very therapeutic for me.
It appears to have a mood lifting quality...without caffeine type jitters. This helps alot with pain issues, I think. It supposedly has some caffeine in it, but I can't feel it. Perhaps the caffeine is complexed to an organic molecule, to lessen its absorption rate. I am very sensitive to caffeine!