The Asus ZenBook S (UX391) is a premium ultrabook that is one of the lightest and thinnest in the market. It weighs just over 1kg and is under 13mm thick.
My review set comes in dark blue with rose gold trim around the edges of the lid to distinguish it from the usual silver-clad laptops. It is also available in dark red.
It is a traditional clamshell notebook. Despite the edge-to-edge glass covering its 13.3-inch display, the screen does not support touch.
The display is surrounded by narrow black bezels, though these are not as ridiculously thin as some other laptops'.
It offers an excellent typing experience, thanks in part to its hinge, which raises the keyboard at an angle when the lid is open.
Asus calls it the ErgoLift hinge, though only the name is unique. I have seen similar hinges on other laptops, including last year's AsusPro B9440 business laptop.
By raising the bottom of the laptop so that most of it is not in direct contact with your lap, the hinge is useful for another reason. It prevents your lap from becoming toasty when the ZenBook heats up while running an intensive app like a system benchmark.
PROCESSOR: Intel Core i7-8550U (1.8GHz)
GRAPHICS: Intel UHD Graphics 620
MEMORY: 16GB DDR3
SCREEN SIZE: 13.3 inches, 1,920 x 1,080 pixels
CONNECTIVITY: 2 x USB Type-C Thunderbolt 3, USB Type-C Gen 1, audio jack
BATTERY: 50 watt-hour
VALUE FOR MONEY: 3/5
BATTERY LIFE: 3/5
Asus lets you increase the fan speed for better cooling, which seems to imply that heat could be an issue - especially when you are separated from its warm innards by only a thin sheet of metal.
I would recommend doing so also to ensure the laptop is consistently running at its top speed. After all, the Intel Core i7 processor in the ZenBook is designed to throttle its speed automatically if it gets too hot.
The faster fan speed does cause more noise, though the trade-off might be worth it.
The hinge also helps to divert the warm exhaust from the laptop's air vents - located at the top edge of the keyboard - upwards, away from your lap.
The backlit keyboard itself has decent key travel with good spacing between each key. The keycaps are curved slightly - Asus calls them dished keycaps - for better typing accuracy.
The touchpad feels tight and precise when tapped. It is a bit shorter than I would have liked, though it is spacious enough to execute Windows 10 multi-touch gestures.
The touchpad's usable area is slightly reduced by the presence of the fingerprint sensor at its top right corner.
All of its ports use the USB Type-C socket, so a dongle is probably necessary for most users. Asus helpfully bundles a mini dock that includes an HDMI port, a USB Type-A port and a USB Type-C port.
Besides its Intel Core i7 processor, the ZenBook also comes with 16GB of system memory and a 512GB solid-state drive. Its performance in the PCMark 10 system benchmark is slightly lower than expected at around 3,258 compared with other recent ultrabooks like the Lenovo Yoga 730 (4,010).
Its battery life was rather disappointing. It lasted just four hours in the video-loop battery test at maximum brightness.
• Verdict: A stylish premium ultra-portable laptop that offers an excellent typing experience. But it runs fairly warm and its battery life is shorter than expected.