The UI is utilitarian—don't expect a Sony-style XMB experience. It is a command-line interface wrapped in a basic GUI. Despite the retro look, the prompts are clear.
The ability to move from a current firmware (e.g., 12.50) to any previous version (e.g., 9.00) without restriction. This is currently impossible through software alone because Sony uses hardware-level protections like e-fuses and encrypted keys in the ROM to prevent rolling back the system clock. ps4 tool downgrade v100 verified
The PS4 motherboard contains two firmware slots— (active) and Slot B (inactive/backup). The UI is utilitarian—don't expect a Sony-style XMB