Instruct: Classify the given Amazon review into positive or negative sentiment.
Query: Flat water, weakest of all siphons

Sucks pretty bad -- water is almost totally flat, even when I do the refrigeration trick that is so sworn on here. The problem is the design itself which purposely limits the amount of Co2 the unit will hold in order for 'safety'. Check out consumer report's review of Soda Makers, and the ISi was rated as 'low fizz'. Waste of money.