Unlike a conventional waterproof fabric, Analogy would fail a hydrostatic head test (if used to seal the bottom of a tube containing water, only a very short column could be supported).
Clothes made from Analogy can also be heavy compared to many examples of waterproof "hard shells" (but not necessarily to the combined weight of these and an insulating layer) and are relatively expensive.
[2] Though the veracity of this may depend on the system it's compared to, as for many applications it means that fewer overall items need to be carried, potentially reducing the total garment count and expenditure.
The high "breathability" of the system makes it more suitable than conventional "hard shell" waterproofs for general use, as opposed to only being used in foul weather.
The main user of Analogy is Nikwax's sister company Páramo with some other small specialist suppliers also producing garments from it.