The Asus Zenfone 4 Max Pro is the Energizer bunny of phones. I could go three days without charging it, thanks to its huge 5,000mAh battery. Asus has also added a reverse charging feature that turns the Zenfone into a power bank to charge other devices.

Despite the larger battery, the Zenfone is only slightly heavier and a bit thicker than typical phones. It is well made with a sturdy metal body. The front fingerprint sensor works accurately enough, though it could be faster.

The Zenfone sports dual rear cameras, with a wide-angle (120-degree) secondary camera useful for group photos. It takes decent photos and the camera app offers plenty of manual settings, like exposure and white balance, for the more savvy user.

Its display, however, is a massive letdown. I was expecting it to match its rivals with a full-HD display or better. Instead, the Zenfone has a HD (1,280 x 720 pixels) display that does not look crisp. It is a shame because it is a decent IPS screen with good viewing angles. Perhaps Asus went with the lower screen resolution to maximise battery life, but it is a deal-breaker for me.

Asus has equipped it with three card slots (two SIM and one microSD), which is unusual. Both SIM slots support 4G networks, though only one SIM card can connect to a 3G or 4G network at a time for data.

As for the user interface, I would have preferred a leaner one with fewer preloaded apps than Asus' ZenUI, but at least the default apps are organised neatly into folders.

It is generally responsive, with occasional stuttering while scrolling through Webpages.

Vincent Chang