it works the same if you apply it to other disciplines. The saying, "a plan is useless, but planning is invaluable". Agile just skips the second part by trying to throw out the first part.

I think a real criticism of Agile would be that it works great assuming a) domain expertise and b) good understanding of how accurate / precise a solution has to be to work.

Agile seems to work best when the domain itself is technology, rather than, say, when the domain is HVAC control or real-time ECMs.