We've had one for over a year now and love it. We never use it for soda, only for the carbonated water. Before purchasing this, we would buy the water in six packs of bottles, so we were always carrying bottles in, and then recycling all the plastic. Our tap water tastes fine, so it works well to make our own carbonated water. We started drinking "fizzy" water when we lived in Europe and just enjoy it.
In our area, it is difficult to find places to purchase the refill tanks of air, so we just order them online from SodaStream. (We can often find an online coupon.) The tanks can't be shipped via traditional UPS, etc., so a service delivers them to our door and picks up the empty canisters. As part of the purchase, you're required to return the empties. I think I have now noticed the tanks at Bed Bath & Beyond, but ordering online is convenient and we order 2 at a time.
For us, it was a great purchase.