The Apple Watch Series 5 smartwatch (prices start at $599) looks exactly like its predecessor, the Series 4.

This is no surprise, considering the Series 4 was the series' first redesign. But the Series 5 comes in new case materials - apart from the mainstay aluminium and stainless steel - there are now titanium and ceramic.

The ceramic watch case, available only in white, is supposed to be very scratch-resistant, while the titanium watch case comes in natural brushed and space black finishes, with the space black finish having a diamond-like coating. I find the natural brushed titanium model attractive.

For this review, I have the black stainless steel model, which looks sleek as well, though the titanium models still look better.

Apart from the new case materials, the biggest upgrade in the new Series 5 is its always-on display (AOD).

With this display, some elements of the watch face will always be visible to tell time, instead of "blacking out" like with previous Apple Watch models.

So if you are carrying heavy groceries, you now do not need to raise your hand to wake the display up to check the time. Just glance at your screen.

The new watchOS 6 has several new watch faces that take advantage of the AOD. One is the California watch face, which has a mix of Roman and Arabic numerals. These numerals, along with the hour and minute hands, remain visible when the watch is idle, while the background and the second hand disappear. They reappear when you raise your wrist to wake up the display.

Unfortunately, there is still no support for third-party faces. The AOD feature would have been perfect for developers to create new watch faces.

You can deactivate AOD for a longer battery life. But I found that even with the AOD turned off, you probably still have to charge the watch daily.

Apple said that with the AOD turned on, the Series 5 will continue to have an all-day battery life.

With the watch paired to an iPhone with notifications turned on, and with a 5km walk (not running in this hazy weather) and a 500m swim thrown in, it still has around 40 per cent battery life left when I put it to charge at bedtime.

Another new feature is the digital compass, which shows direction and elevation.

For those who like hiking, this compass app is handy and could help them from getting lost in forests. I drove up the 106m-high Mount Faber and found the reading at the carpark just below the peak to be 96m - pretty accurate.

Also new in the Series 5 is a feature that allows international emergency calling (in more than 150 countries) without your iPhone. This feature is supported only by the Series 5 cellular models and it works even if no cellular plan has been activated.

Simply press and hold the side button to call the emergency services of the country you are in. I did not try this mode as I did not want to waste the time of the emergency services. But this might be a lifesaver in accidents and other mishaps.

Elsewhere, the Series 5 has the same health and fitness features - such as heart-rate monitoring and electrocardiogram (ECG) - as the Series 4. The watchOS 6 also introduces menstrual-cycle tracking for women.

On the down side, there is still no sleep tracking mode on the Series 5.

In terms of step tracking, the Series 5's readings were very close to those of my calibrated Series 4 watch, with a difference of only 1 per cent. That is really good for a smartwatch that has not been calibrated.

Tracking my usual 5km jogging route using Global Positioning System, the tracked distance was only 20m off.

For swims, the Series 5 is equally impressive. It was able to accurately pinpoint the number of laps I did and the kind of swim strokes I used.

Though its improvements are incremental, the Apple Watch Series 5 is still the best smartwatch in the market, with its sleek design (especially the new titanium case), useful health features such as ECG and superb overall performance.

For those using Series 4, it might not make sense to upgrade. But for those using Series 3 and earlier models, it is a must to upgrade to the Series 5.