With smartwatches having fitness-monitoring features, you might think fitness trackers are becoming obsolete. But fitness trackers still hold a huge advantage over smartwatches - their much lower prices.

Instead of costing from $500 to more than $1,000, Garmin's latest fitness tracker vivosmart 4 costs $199. Yet it is packed with features such as all-day stress tracking, advanced sleep monitoring, a VO2 Max value or maximum oxygen consumption calculator and a Pulse Ox sensor that measures your body's blood oxygen saturation level or SpO2.

In addition, the vivosmart 4 has a unique feature known as Body Battery. Using a combination of your stress level, heart rate variability (HRV), sleep and physical activities readings, it gives a gauge of your body's energy reserves on a scale of zero to 100.

So, if you are having enough rest, you should be waking up to a Body Battery of close to 100. And during the day, the Body Battery will tell you how much "juice" you have in your body.

On the downside, the vivosmart 4 lacks built-in GPS. It does not have connected GPS, a feature which uses your smartphone's GPS to track distance during runs. However, it will automatically detect when you are working out - walking, running or cycling - and tracks these activities.

Design wise, the vivosmart 4 looks pretty much like any other wristband fitness trackers. But it looks much better than its bland-looking predecessor, the vivosmart 3.

The vivosmart 4 sports a unibody design with no buttons. The watch comprises a rubber wristband with a rectangular Oled touchscreen (48 x 128 pixels), which has a metallic bezel. Colour combinations include berry wristband with gold bezel, grey wristband with rose-gold bezel, light blue wristband with silver bezel and black wristband with slate bezel (version tested).

You cannot change the wristband of vivosmart 4, unlike with some other fitness trackers. So, you have to make a choice and stick with it.

Its watch-like clasp fits securely on the wrist and feels comfortable even when wearing it 24/7. The monochrome display is easy to view even under bright sunlight. It is a cinch to toggle the various menus on the display with upward and sideways swipes.

In terms of steps tracking, the vivosmart 4 is accurate with a difference of a mere 2 per cent when compared with my calibrated Apple Watch Series 4.

But with the lack of GPS or connected GPS, the distance it tracked during my runs was way off. My usual 5km jog was registered as a 7km run.

However, the sleep monitoring function of the vivosmart 4 is much improved from its predecessors and other Garmin fitness trackers.

Previously, when I put Garmin fitness trackers on the table, they would track that status as sleep. Not so with the vivosmart 4. In addition, the vivosmart 4 can track rapid eye movement or REM sleep along with light and deep sleep. I found it was able to accurately track the time I went to bed and woke up, as well as the time when I woke up in the middle of the night.

However, the Body Battery feature did not work well for me. There were times when I woke up feeling refreshed, but my Body Battery showed a score of only 78,compared with a score of 98 on other days. At the end of some days when I did not feel tired, it displayed a score of 20. So, just take it with a pinch of salt.

The best part of the vivosmart 4 is its long battery life. Most fitness trackers last two or three days. But vivosmart 4 was able to last five days - even with SpO2 tracking when I was sleeping - before it needed to be charged again.

• Verdict: Apart from its lack of GPS, Garmin's vivosmart 4 is the fitness tracker to get if you just need one to give you a quick overview of your health and fitness status.