They keep your knives securely contained and look great on the counter. Magnetic knife blocks are good for storing knives in a simple way and, at the same time, allowing them to stand out visually. However, they can pose a safety hazard if the magnet is not strong enough. They can also degrade knives if the magnetic strip isn't cleaned properly.
I know I'm going to get out of here, which may seem strange because what has a knife block ever done to me? Nothing, really. They're fine if you have counter space and a set of knives perfectly matched to fit the limited number of slots of different sizes. But that's not my case and I don't think it's the best solution for most people either. A chef's knife generally measures between 6 and 12 inches and has a long blade that curves upward at the end.
It can't chop or dice as well as a chef's knife and isn't as handy for peeling vegetables or fruits as a peeling knife. Sohla, on the other hand, loves her canvas knife roll, which is made of real, natural canvas that almost definitely doesn't let a blade be cut so easily. Instead, I think it's usually a smarter approach to create a collection of knives little by little, investing more in one or two chef's knives, possibly splurging on a santoku or a good slicer, and saving money elsewhere on cheap peeling knives and bread knives. It's smart to put them on knives in a knife bag, as already mentioned, but they're also essential if you store your knives in a place where they can be hit freely, as they'll protect the edges of the blade and you.
Check out the magnetic knife bar option to keep your kitchen clean and modern without the worries that come with a universal knife block. The magnets are strong enough on the knife strips, but not so strong as to ensure that the blade cannot be removed forcefully. Both knife storage solutions offer much more flexibility than knife blocks, without sacrificing safety or aesthetics. Storing knives in a drawer doesn't mean putting your knives in with your other kitchen utensils, or even placing them in a drawer-sized version of a knife block.
Keeping your knife loose in a drawer with other utensils is a good way to wear down the blade prematurely, and leaving it on the counter is no use either. If you don't clean the magnetic knife holder regularly or if you store dirty knives, particles can scratch the knife. And since knife blades are exposed, they can pose some safety risks if you have small, curious hands in the kitchen. Some people worry that the strips that leave the magnetic rails exposed could damage the blade of a knife when you place it on the holder, but I've never noticed any problems.
With the saya on, you can safely store a knife in a drawer and then put it in a day bag for a picnic without having to carry a full roll of knives.