Just yesterday I started a VM of beta2 of HaikuOS for a good dose of nostalgia. Some observations: the responsiveness of the UI is instantaneous. So much so that it feels alien nowadays. Also the UI does not waste space, but at the same time it does not feel cluttered. Laying out windows feels more organized than Windows 10 or recent macOS. I can't really point out why. Lastly, having dedicated window borders is so useful for aiming the mouse pointer when reszing.
At some point our UIs became more a design than a utility.
