I read most of the primary sources (of the few) about Huns, and the image of the Huns in your question is based on the work of Jordanes from the 6th century: the Huns were wild, barbaric, and devastating to Rome. Jordanes' point is that Attila was born to punish the world (the christian world) for its sins. Jordanes exaggerated to bear out his view, we can say that, as another source called Priscus in the 5th century sates less. Priscus was an eastern roman diplomat, he met Attila in person.

Yet, Huns caused damages to Romans, they were especially successfull against Eastern Roman Empire. In order to save the capitol city Constatninapole (also a center of trade), Eastern Romans tended to pay tribute to Huns already in the early stages of the wars. Thus, the impressive battles happened not here, but in the Western Roman Empire.

Western Roman Empire at the time (450) had very weak central authority and territorial integrity. There is even a debate when did Western Roman Empire fall, because the situation before the consensual 476 AD barely differs from the years after. Vandals already invaded first Iberia (409), then pushed by Visigoths (418) the Vandals conquered North Africa. The chaos rose during the next Roman emperor Valentinian III (425-455). He was a child, thus his mother Galla Placidia tried to rule the empire, but a Roman general Aetius had the real influence in this war-torn period. Galla Placidia and Aetius had a constant rivarly. Aetius had good relation with Huns, at age of 17 he spent some time amongst them. In this era the Roman army was already full of german, gothic and nomadic mercenaries, and it happened frequently that foreign authorities as allies fought in internal wars of the Romans. The Huns were such ally of Aetius at the beginning, they confronted with the supporters of Galla Placidia not once. In 450 Attila started a champaign against Visigoths in South Gallia. Moreover, in 451 Attila used an intrique of the emperor's court to claim the Western Roman Empire, so allied with Gepids, Ostrogoths, Franks, Toringi and other Germanic tribes, he also attacked Roman Gallia. Aetius managed to stop Attila in Catalaunum the same year. Interestingly, Hunnic mercenaries fought on Aetius' side as well. Attila died in 453, and his heirs could not keep his tribal alliance together, the Hun Empire fell apart.

This brief summary might help to see the late Roman Empire more complex. I mean, not just Huns were devastating to the Romans, but also the political situation.

Now let's see some other factor too!

Unfortunately I am not familiar with (very) early medieval Germanic warfare (it is relevant as Germanic chiefs blended into the late Roman army), hopefully someone can help us out with that part, but I can introduce the Hunnic warfare.

First of all: speed. Hunnish armies moved faster as "non-nomadic" armies because they had better horses and better logistics. Huns knew sige weapons and they had allied gothic troops which moved the same speed as the enemy, but the Huns themselves could ride 60-70 km a day. To compare, medieval average was 30-40 km. This means, if the Huns wanted it, they could surprise the enemy anytime. I wrote "better horses" which means they had a smaller type of horse which was faster and undemanding, those horses were fine under any "diet" and weather conditions. The Huns used light saddle, and that saddle was also comfortable for the horses. One warrior had at least two horses in order to switch, if the animal became tired, so they could ride continuosly if needed. The supply of the army was very primitive, thus effective. In a hurry, they simply hunted animals, and they dried the redundant meat for later use. Classically they moved with a herd of steppe cattle, and they slaughtered some of the cattle time to time. They used every part of the cattle: the meat for nutrition, the skin for leather body protector, the horn for horn (sound-making for navigation in a battle), the bones for arrow heads. They used obviously very much arrows, so by bone arrow heads they had unlimited ammo. Huns knew metal arrow heads though, just as they had proper iron swords. By this instant supply technique, the Hun army was highly mobile.

Huns wore light, leather-based body protection, so they could move quicklier in battles too. During a battle they were disciplined in a way: every squad had its uniqe horn-signals (sort of bugle call), so the squads were well aware of the current orders. Although Romans fought in formations and the swordsmen helped each other, yet in general they preferred face-to-face combats, while nomads were rather cooperative. A nomadic horseman aimed to injure as many foes as possible, not to kill them. Five horsemen in a row meant five injuries from five different nomads, while the continental warrior was still looking for one particular horsemen to obtain glory. The same goes for use of bows. The targets were directions, not persons. Patches of foes received arrow-showers, altough if needed, nomads could shoot individual targets as well (otherwise they must have been unsuccessful in hunting).

The most successful nomadic tactic (it applies also other nomadic people before and after Huns) was the fake-retreat at the early stages of a battle: this caused the break down of the formation of the enemy if they were undisciplined. The undisciplined or unaware enemy started to chase the nomads, while they shoot backwards, causing injuries. After this phase, the nomads turned back, and started the real combat.

tl;dr

Huns were not the only threat to the Western Roman Empire, and they mentioned as a devstation only by Jordanes not confirmed by more credible authors, but the Huns had some unusual features made them successful indeed. I would underline the speed of the Huns: once they won a battle, the enemy had never a chance to retreat and reorganize properly, because the Huns could have ride twice as fast.

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