Does it have the potential to brick the device? Yes.
Will it void my warranty? Definitely.
Will I stop getting updates? Yes, if you install a custom ROM.
Will the cops show up at my front door the next day? Yes, but only if you're Chinese ;-). And even then, only if your police administration is near enough to Beijing.
And you should be aware that it is a security risk. A root user has access to the entire phone, including all of its functionality, and the memory of all running applications. A backdoor could be installed in a custom ROM. It might not even be to your disadvantage, but your phone might become part of a botnet.
