Stevia has a number of benefits. The packets are an easy way to use it as a sweetener. The liquid is even better IMO, and comes in flavors and is easier to dissolve in everything. I don't even use sugar anymore unless i'm cooking.
In the garden, stevia is a natural insect deterrant and can keep unwanted pests away, such as aphids as i recall. I'm growing about 4 plants in my garden as i type this. The leaves are large and green and have a natural sweetness to them that is quite pleasant and would make a hell of a mojito or mint julip additive. Typically the leaves are harvested at the end of the season, dried, and crushed to be used in making an extract.
It's easy to grow as well. My plants are well over a foot tall in just 2 weeks. Don't bother with seeds, go right for a seedling. Seeds are kinda hard to germinate.