I've used a few devices in my time... Apple (very short period of time, curiosity led to boredom there) Sony and Huawei... personally, I found all their personalising stores nothing compared to Samsung. Samsung have so much quality and choice.
I am guessing there maybe many people out there that don't use it, not tried it or even know about it so if you're one of them reading this... go to it and try it. Plenty are high quality and free... some are premiums where there is a price charge but you can add to your watch list and see if it gets a sale price or goes down to free.
What's also great is that I've built a massive archive on my Samsung account so both my Samsung phones can get the same themes I've purchased or downloaded to my account. When I upgrade they can also move over to my new phones if I log in with my same profile.
It's not just themes... you can get wallpapers and even icons so some people may prefer icons just for ease of use for their eyes.
I just thought I'd give a shout out to a Samsung feature that is under rated in my opinion.