We have a SodaStream. We like it mostly for flavored water (there are flavoring bottles available- natural flavors with no sweeteners). The sodas all do have either Splenda alone or a mix of Splenda and sugar, but to me, they don't tase weird. The "diet" flavors are Splenda, and the "regular" flavors are a mix of Splenda and sugar, so they have a lot less calories than non-diet canned sodas. I like the Diet Pink Grapefruit, Lemon-Lime, Cherry Cola, Ginger Ale, and Cranberry-Raspberry sodas. DH and DD love the Energy drink- they say it tastes like Red Bull. There are around 40 or so flavors available on the SodaStream website.
The CO2 canisters are available at BB&B (and other places)- turn in the empty canister and get a full one for around $15. Each canister has enough fizz to make 60 liters of soda. The soda mixes are mostly $5- each bottle has enough to flavor 12 liters. They can really save $$ for folks who drink a lot of soda and/or fizzy water. Also, no more lugging cases of soda home from the store, and no more bins full of empty cans/bottles.