The adjective "geil" used to mean "horny", but that meaning gets lost more and more, since the word has been used in the sense of "awesome" in youth slang. More precisely, that started in my youth in the 1980s, and the word has been kept with that meaning since. So, as long as you don't call a person "geil" in a situation with sexual context, there is no room for misunderstandings.
"Sowas von" is a more recent slang expression to emphasize an adjective. When you call somebody "sowas von blöd", you basically call him a complete idiot. "Sowas von lecker" is a huge compliment on the food you just had.
So, "sowas von geil" does not just mean "awesome", but rather: "absolutely awesome".
Some other expressions with a similar meaning are:
- absolut genial
- einfach fantastisch