I have a FIZZ. It takes the large and small CO2 canisters. The large canisters last more than twice as long as the small. To make good soda you should use refrigerator cold water. So, get a couple extra bottle and prefill and keep them chilled. Chill your syrup, too. However, I noticed that the regular cola syrup is pretty thick and doesn't mix as well when cold. The machine is easy and fun to use, but does require a little getting used to and some experimentation which is actually fun IMO. I use only diet soda and have only tried the regular cola out of curiosity because it does have fewer calories than sweetened sodas. The product is good and it will probably get better because they do have room for improvement in getting it to be a little easier to use and standardizing the finished drink. Odds are that will give them the ability to resell you on a new unit every couple years, much like Gillette and Schick.