I first tasted stevia at the Ojai Spa several years ago.  I was truly impressed.  They used it in everything, and there was no dectable aftertaste to my palate.  I immediately went to our local health food store and purchased some (powdered green stuff) that had no resemblence to the what I had.  Last year I bought a product called 
Sweete, a stevia product.  I use it in my tea occasionally.  There is no bitter aftertaste.  But, depending on the tea, there is a off-taste sometimes imparted.  It's okay, but it's not quite there yet, for me.  Perhaps Truvia is a better quality product.  I plan to give it a try.  If you do so soon, I'll be interested in your thoughts.  Thx.