Hardware

Compared to its $200 sibling device, the ZenWatch, ASUS' newer and cheaper VivoWatch is all about wellness: steps, calories, heart rate, sleep quality and even UV level. With the exception of caller ID (with vibration alert), you won't be getting any notifications from your phone. In other words, the VivoWatch is less of a smartphone companion and more of a fitness wearable. The company admits that both the ZenWatch and the VivoWatch "target distinct user groups with highly crafted, but varying features," thus implying that there isn't much overlap between the two groups.

It's not every day that you come across a sports watch with such understated elegance.

In terms of design, what you get here is a curved Gorilla Glass 3 touchscreen encased within a slightly rounded stainless steel frame. It looks similar to the bigger ZenWatch from afar, except it comes with a glossy metal finish instead of a brushed one. Over time, I became a fan of the VivoWatch's decent looks: It's not every day that you come across a sports watch with such understated elegance. But that's obviously subjective, and a couple of my friends did say they'd prefer something that looks a bit sportier to reflect its purpose. At the risk of sounding picky, maybe the glossy frame could use a brushed finish instead to keep fingerprints off it.

The VivoWatch has decent protection against liquids plus dust -- IP67 versus IP55 on the ZenWatch, meaning it's both dust-tight and has been certified to remain intact under one meter of water for 30 minutes. For obvious reasons, the bundled strap is made out of plastic instead of leather, but you can swap it with any standard 22mm strap.

For the sake of extending the battery life to up to 10 days, the VivoWatch uses a combination of ASUS' self-developed, real-time OS called KoodOS; a low-power processor; and a 1.28-inch, 128 x 128-pixel, low-power, black-and-white memory LCD. The screen works very well under sunlight, and it's also backlit for indoor usage. To juice up the watch, just snap the small charging cradle onto the back of the body and leave it there for between one to two hours.

To use the watch, you need to click on the home button on the right to unlock it. From the watch face, you can swipe horizontally to cycle through the pulse reader, the alarm, the daily activity log (for steps and calories) and the UV level detector (a feature also found on the Microsoft Band and the Samsung Gear S). You can also swipe vertically to go through the daily exercise log (total exercise time and period of aerobic activity; more on that later), daily sleep log (total sleep time and period of comfort sleep) and a happiness index based on a combination of exercise quality and sleep quality, plus all-day heart rate monitoring.

To fully appreciate the VivoWatch, you'll want to turn on its Exercise Mode, which uses a front-facing LED to indicate whether your heart rate is within the optimal range (green) or is too intense (red, with vibration alert), according to your profile. To toggle Exercise Mode, simply hold down the home button for about four seconds; when finished, you can do the same to quit this session, and then you can sync the exercise data to your phone over Bluetooth.

Even though Mio is the true pioneer of the heart rate-zone LED indicator, ASUS improved upon it by using a much larger LED strip for easier viewing, and that, in turn, became a motivation for me. In this mode, you can also swipe horizontally to see a live chart of your heart rate, burned calories and steps, though I tended to just stick with the default stopwatch screen.

Now, it's worth pointing out that despite its name, Exercise Mode can only track one type of workout for now: running. If you want to monitor specific types of exercises, then this isn't for you -- as is the case with many other fitness wearables made for casual runners with basic needs. On a similar note, the VivoWatch doesn't track your distance, so serious runners may want to look elsewhere (we'll explore some alternatives farther down in this review).

While I didn't have other heart rate monitors on hand to do a direct comparison, I did notice that the VivoWatch's reading occasionally fell short while I was running, and then went back up when I stood still, instead of slowly decreasing as it was supposed to. My watch was definitely secure on my wrist, although not too tight as per instruction. Maybe it was the sweat? No idea. As it happens, our friends over at DC Rainmaker and CNET found the same problem with the Fitbit Charge HR and Fitbit Surge, so this is likely a common flaw on devices with the same type of optical sensor. The only thing we can do is to make sure that the sensor is clean, and that the watch is worn securely.

When you're not exercising, the VivoWatch will poke you with a vibration alert if you've been idle for too long, and it'll also congratulate you when you meet your daily goal for either steps or calories, which can be set in the smartphone app. Toward the end of the day, the VivoWatch will automatically track your sleep. So far I've found it to be pretty accurate.

Companion app

Before you can use the VivoWatch, you have to first install the HiVivo app on either your Android or iOS device, set up your profile (including age, gender, height and weight) and then pair up with the watch. Every time the watch is paired, the app checks for firmware updates. When it's available, be prepared: The update process not only takes at least 10 minutes, but also requires you to keep the app active, otherwise you'd end up with an error (at least it did on our Android handset). It was very surprising to encounter such amateur hour coming from ASUS, but even throughout my testing period, the VivoWatch's firmware version went through several revisions -- from a buggy 2.05 to a more stable 2.11 -- so at least it's apparent that the company is actively fine-tuning the product.

As you'd expect, the app gives you a good overview of your fitness parameters in the form of charts, so you can easily track your progress throughout the day or week. But of course, you can already see your basic daily data on the watch's reasonably sized screen. It goes without saying that your fitness data is synced to the cloud, so even if you switch to another phone, you'll be able to restore your charts.

The extra bit of info that you do get in the app is a chart of your heart rate throughout the day, and an indication of how much of your exercise was aerobic and anaerobic. For those who aren't familiar: Unless you're an athlete or have specific fitness goals, chances are you only want to do aerobic training just for the sake of staying healthy, so you'll find the app's Exercise Mode chart useful for analyzing your performance. Unfortunately, ASUS says you can't export the data to third-party apps like RunKeeper and Strava, so you're stuck with HiVivo and its website counterpart that ASUS is still working on.

Another interesting feature in this app is the Network section where you can view your friends' happiness index, as well as their workout time and sleep time. You can view this as a competitive element, but there's also a "Like" button next to each name for a bit of encouragement. Sadly, I didn't have any other VivoWatch users to add, which makes us wonder: Maybe ASUS should consider selling discounted bundles to couples and families? We'll let their business folks do the maths.