There are many benefits and the first, very obvious: filtration based on the principle of removing as many particles (dirt, moss, trash) as quickly as possible and separating them from the waters in the pond, making them unable to cause harm.
A "normal" filter can only retain what it can hold… and the waste it keeps will gradually clog, corrupt and degrade the filtration system. With a drum filter, this is not something worth discussing. Subsequent filtration systems, such as biofilters, are also less prone to overloading, allowing in many cases to reduce power and increase equipment durability.
The second big advantage: as long as you have reasonable UV energy, the water will be transparent throughout the year. No problem!
The third advantage: stopping the filter cleaning job by replacing the filter, changing the membrane or scrubbing with a brush, the drum filter automatically cleans it. To be honest, this filter still requires a minimum of attention because it is a machine, and therefore, some minor interventions are necessary, but absolutely nothing binding.
Finally, each brand and model has its own characteristics: it's up to you to determine the exact type of filter you need.
Pump fed or gravity mode, stainless steel or polypropylene, with or without biofilter? These are the first selection criteria but the most important is its size. Remember that the filter should never be too big: the frequency of rinsing will be appropriate, pleasant (3 to 4 times per hour in summer and about 10 times per day in winter).
On the other hand, a filter too small will consume more water because it will have to be washed more often.