I've never used the powder form of stevia, but using the liquid-from-a-dropper form VERY sparingly works for me. I've never sweetened my coffee, ever, but will mix a few drops into a very large batch of iced tea, coconut milk-based desserts, homemade lemonade, that sort of thing.
I can't do much fruit at all, for metabolic reasons. A touch of stevia here and there helps me avoid the inevitable fruit sugar issues (energy crashes, cravings, fruit binges and weight gain).
Edited to add: I've never noticed any aftertaste at all with liquid stevia, to answer the OP's original question.
I tried it and not like. Basically, after being diagnosed as type II diabetic, I have abandoned all sweet (and carbs). The sweetest thing I eat is dairy...
My wife bought me stevia thinking I might like it, but after no sweet for a year, it was sickly sweet.
Even before |I was diagnosed, I had a vision one day of giving up all sweet, I was a honey addict at the time.
It's not as difficult as I imagined.
The only time I use stevia is when I occasionally make a paleo dessert, like pumpkin pie with an almond flour crust. I use the pure white extract with no bulking agents to make it spoonable, and I use it along with a small amount of real sweetener. If I recall correctly, the last pie I made contained one tablespoon of maple syrup and a quarter teaspoon of stevia extract. Without being combined with at least some real sweetener, I find stevia unacceptable.
The "real" stevia in powdered form is not as bad as the powdered white stuff - it has a leafy green colour to it. In coffee is still not great, but in herbal teas is actually really nice. I make a mean fake champagne with lemon myrtle, peppermint and stevia leaves made into a tea, chilled and then put through a soda stream.
It tastes nasty because it actually tastes like that gross black liquorice candy. You know the kind you used to get trick or treating and then desperately tried to trade away for something even vaguely palatable.