Concrete is the most careless, promiscuous stuff until it is committed, when it becomes fanatically adamant. Liquid rock, concrete is born under a sign of paradox and does not care. It doesn't care about anything, lazy and in love with gravity but only half in love [...] Promiscuous, doing what anyone wants if the person is strong enough to hold it, concrete is a slut, a gigolo, of materials. Every other material - wood, clay, metal, even plastic - has self-respect, a limit to what it will suffer to have done with it, and at the same time is responsive within that limit, supple in the ways it consents to be used. Not concrete.
I'm not sure if this is actually true or if the author is simply indulging in metaphor... I've found that the amount of water and the nature of aggregate can change the behaviour of concrete dramatically. However, if the formwork and the aggregates are chosen so that they complement each other, concrete can take on unlimited disguises. For instance, it can look like lace:
These prefabricated panels at Nottingham Contemporary Art Gallery were quite amazing in their detail and texture. Although I think the most amazing part would be to see the molds that made these panels. For concrete, the most effort is put into the things that will never be seen.
At the Lloyd's Building in London, the concrete is detailed like steel, with connection pieces and bolt holes: