At GDC in March, Microsoft demonstrated a unified Xbox user interface designed to work across handheld devices, consoles, and cloud gaming platforms.
A video of the keynote published on May 7 provides a closer look at the interface. Jason Ronald, VP of next generation at Xbox, stated that the team aims to deliver a consistent experience that feels familiar across devices, addressing fragmentation noted by players.
Visual Changes
The console homescreen shows slight differences: user profile in top right, three ad slots along bottom (instead of four). The handheld interface is similar to the console version.
The PC app interface resembles the new Xbox Cloud Gaming UI, which includes new animations, a library section, and rounded design. Ronald noted the UI will not be identical across all devices due to differences in screen size and input modalities.
Store Changes
The Xbox game dev update video also showed what appears to be a new Xbox store on Windows. Microsoft declined to comment on the new Xbox UI and store changes.
Source
The full GDC keynote is available in Microsoft's Xbox game dev update video (nearly 90 minutes).