I am absolutely certain that there are better paddles out there. In the case of this one, the letters start to curl up, as they are not anchored to the interior of the paddle. It's also pretty small. But, what is really required of a paddle? Can you smack someone with it? Then it works.

Granted, you could also use a ruler. But a ruler isn't as cute as the xoxo paddle. And though I've seen some complaints that the letters don't show up on skin, I have actually gotten them to show up as a reddish imprint for a few seconds. But no welts. Then again, I don't think I'm slapping hard enough to leave welts.
One exceptional feature of the xoxo, though, is that it's very similar to leather without actually requiring the flesh of a cow. If you're concerned about bovine well-being, this is great.
There is also the convenience of the xoxo - it's small, but also can be stashed away easily. It can be hung on a wall if you're proud of it. It's easy to grab and hold, and it doesn't fly out of your hand during use. I imagine that could be a drawback with a ruler, as well as a potential for sharp edges.

It does provide some extra leverage during the slap, so if you, like me, have trouble getting a satisfying smack with your hand alone, a paddle like this could be useful. It's got a flexible plastic layer inside, between the layers of non-leather material. It's possible that it could crack, I suppose, under extreme bending. I did once break an unbreakable comb by bending it back and forth on the same stress line over and over. This is most likely a similar material.
I do admit that I like having this paddle, and it's great for travel. But my partner and I have found we somewhat prefer to use a nice whip. It's much more luxurious.

You may note I've included a rating on the noise level - it seems pretty obvious that there is a potential for loud slaps. But the loudest slap I've heard it produce could be muffled by a regular wall.