First things first, welcome to the Apple Communities Brazil!
I've checked on a lot of reviews from different specialized pages of the tech and mobile world myself, and they're all unanimous about one thing: the iPhone X is the best iPhone ever made!
Of course nothing is perfect, being a technology device. It is susceptible to failures and bugs, but in general terms the "X" is awesome and groundbreaking. I'm pretty sure there's no "misbuy" regarding it.
You can make a quick search around the Communities to see some people reporting problems, some are the device's failures, and others are human's mistakes. But overall it doesn't have big issues. I'm sure you won't regret having this great device on your hands.
Hope I could be of help,