Since it's endorsed by MKBHD, I have high standards going in.
The actual collection of wallpapers is baller. Abstract, nature, 3D, photography, etc. I think the catalogue has cohesion, nothing made me go "the heck is that doing here", there's just enough different styles for everyone. But before you download it, just keep the following in mind:
Every wallpaper can be downloaded for free - in SD. If you want the HD version of any of them, you have to pay. Maybe give users a way to earn 1 free wallpaper a month or something.
Also, the SD wallpapers are all locked behind a 30 sec ad in order to sustain the model.
So basically, theres no quick downloading your 5 favorite wallpapers and seeing which you like more as your actual wallpaper with your actual icons and layout, because you'll have to wait a minute of ads for 2 wallpapers. Is it kind of a lot? Yes, it's a free model and I get why, but It's pretty bad and cumbersome for the user experience. I can go to pexel for example, and download as many full resolution wallpapers as my device can hold with no slowdown.