Fever-Tree Bitter Lemon (I'm not sure if they changed the name to Lemon Tonic since I got this bottle or if it's available in different names depending on the market) is quite simply tonic water with added lemon juice - which means that in addition to being a sparkling lemon soda it's also got the bitterness of tonic water.

Nose: Cloudy bright yellow in colour with a bright and distinctive aroma of lemon. Mouth: Very fizzy with tart and refreshing lemon in the beginning and the bitterness of the quinine taking over as it fades out. It's a delicious and perfectly balanced soda on its own, but it could of course also be a versatile mixer in fizzy drinks even though it might overpower gentle spirits.

Fever-Tree themselves suggest the drink Yellow Fever (fill a Highball glass with ice, add 1 part vodka, 4 parts Fever-Tree Bitter Lemon and 30 ml fresh orange juice, stir and garnish with lemon zest) but it didn't really appeal to me. Instead, I found an interesting recipe in the Jan/Feb 2014 issue of Imbibe Magazine - the Cobble Hill Variation by David Little of Barnacle in Seattle:

Fill a glass with crushed ice and add 45 ml Fever-Tree Bitter Lemon (the recipe says 15 ml but I think that's a mistake - try for yourselves), set aside. Combine 37 ml Fernet Branca and 37 ml Carpano Antica Formula in a shaker and shake until chilled. Strain over the crushed ice and soda, serve with a straw - and wow, really powerful stuff! Lots of flavours fighting for attention, yet still surprisingly refreshing with a minty, herbal smoothness and a slightly bitter finish. I have to admit that I wasn't sure that these elements would work together, but they sure do!