A Limoncello Soda is a refreshing way to drink Limoncello on a warm summery day. An alternative to this recipe would be something like a Limoncello Spritz if you had sparkling wine on hand. I think additionally, if you were so inclined you could call this a Limoncello Fizz, as it does bear resemblance in flavor and technique to something like a Gin Fizz.
This drink is designed as a before-dinner drink, something you can sip on in the waning daylight hours. I think a nice Limoncello, especially one with cream is a wonderful digestif, but I personally prefer something a bit lighter than a straight liqueur for pre-dinner drinking.