We bought one of these which was immediately replaced with another* -- and both were faulty.
You are given four fizz levels from which to choose. Whatever option was chosen, after a 20-second pause, '3' was delivered.
This was invariably accompanied by a great din and when pressure was released, a fair bit of water on the worktop.
Not having to twist the bottle into position is a real advantage, but other Sodastreams (our Source is one) have the same feature.
The Titan is overly large, and it has to be plugged in.
Altogether a poorly thought-out product. The metal version of the Sodastream Source is definitely a five-star buy. The Titan isn't even a two.
*admittedly, this was when the machine was brand new, and supply constraints suggested something was amiss. But buy a 'Source' instead.