The beta is limited to users with Sprint, T-Mobile or unlocked Galaxy S9 devices. Sorry, Verizon and AT&T users.
It's unclear how long after registering for the beta your device will download and install the first beta update. Outside of including One UI enhancements, the update includes Android Pie 9.0.
Samsung revealed One UI, a complete interface overhaul for its mobile devices, during the company's developer conference.
Samsung has long been known for, and heavily ridiculed, for its heavy-handed approach to customizing the Android operating system. Whether it was called TouchWiz or Samsung Experience, the company's proprietary Android skin has had redundant features, apps, and unnecessary bloatware.
According to Samsung, One UI strips away the unnecessary features and forces users to focus on the task at hand, while making the company's devices easier to use.
For example, the Messages app will now place a list of conversation threads halfway down the screen, making it easier to reach the top conversation when using the device one-handed.
I signed up for the One UI beta on a Galaxy S9 roughly 30 minutes ago, but the device has yet to receive the OTA update. However, several users on this Reddit thread appear to have successfully registered and begun the OTA installation process.
Samsung expects the One UI update to officially rollout starting in Jan. 2019 for the S9, S9 Plus, and Note 9.