I wasn't considering it for us personally - I was idly thinking about how to build a raised paved raised patio, googled and saw these. Was a bit unsure about strength, but thought it was a good way of not having to move a fucktonne of rubble to raise the ground height and ensure proper damp proofing adjoining the house.
I'm not sure I'm convinced about the risk of sinking. You'd obviously have a solid footing underneath - as you would with anything. The question then is if you have to make 25 footings or something is it actually saving time?
In terms of rats, curious as to why is this a greater issue than with wood decking? Or is it equally an issue there too - which would be good to know as there's a bit of the garden we'll add a deck to... eventually.