I think its fair to say that acts of brutality were pretty common in ancient warfare but this seems to have gone above and beyond the normal horrors of a city falling. Outside of Carthage and Rome what did contemporary commentators think of the act? Did it effect Rome's relations with other nations?
I would argue that the Sack of Corinth was just as thorough and calculated in its brutality. Both occurred in 146BCE, and both were designed to demonstrate the Republic’s auctoritas (authority, power) absolutely and completely.
By callously annihilating the cultural centers of two former rivals, Rome gave practical evidence of the coming new order. The Achaian League’s last stand in the face of Roman intimidation is a tale unto itself, but the fact that it ended in a near-identical result to the Third Punic War was certainly no accident.
You must also remember that this was an era when Celtiberian (Spanish) Numantia was utterly destroyed a little over a decade later — and this by a self-proclaimed philhellene and man of culture, Scipio Aemilianus.
See also the doomed rebellion of Aristonikos, the last king of Hellenistic Pergamon in Asia Minor. Though his forces were more successful than Diaios’ defiant Achaians at Corinth, the result was the same. Indeed, Aristonikos’ utter rout of a Roman consular army led to the king receiving the consul’s head as a trophy of war. Such disrespect for Rome’s authority was not to be tolerated, and as a consequence Aristonikos’ remaining supporters were trapped in one last fortress and poisoned.
The Sack of Carthage was therefore far from extraordinary, and indeed was a premeditated instrument of Rome’s nascent imperial system. Somewhat like the Assyrians of old, Rome’s brutality was intended to intimidate the Greeks and the wider Mediterranean world as a whole.
This policy had mixed results — and Rome would come to regret their grasping aggressiveness when Mithridates Eupator was welcomed as a liberator in Rome’s Asian provinces. But that is a tale for another time.
Source: Peter Green’s incomparable Alexander to Actium/Polybius’ writings on the rise of Rome.
Edit: A good secondary source for Scipio Aemilianus in particular can be found in Adrian Goldsworthy’s In The Name of Rome. The book is organized as a series of chapters on notable Roman commanders, and Scipio’s chapter is a valuable window into the world of the late 2nd century BCE.
but this seems to have gone above and beyond the normal horrors of a city falling.
Is this the case? Was the taking of Carthage particularly more brutal than any other contemporary conquering of a city?