I've been using powdered stevia for the past two years, ever since I realized that sucralose (brand name Splenda tm) is NOT a natural product, but one that has been tampered with chemically. I use stevia to sweeten coffee, tea and even cook with it. More and more products that contain stevia are being introduced in the U.S.
I've experienced no problems with stevia or any side effects, which is not true with other non-sugar sweetners (such as aspartame, which can cause headaches and memory loss). If you're accustomed to beverages and foods sweetened with sugar, it may take a bit of adjustment to the taste for you, but since I have avoided sugar for years (it makes me lethargic), I didn't notice any "off" taste or aftertaste at all.
I hope you enjoy stevia. The package will probably give you instructions about how much to use. If not, try a search engine that compares the amount of stevia that creates the same sweetening level as sugar. Good luck!