Syncs good with the phone. Battery life is excellent only have to charge every other day. Tracks all activity.

I keep track of calories burned, heart rate and Sleep. Quick charge and last long time. It’s thin and very comfortable.

I had a few hesitations purchasing this device at first looking through online reviews and what not, and was mainly deciding between this device and the Fitbit Charge 3 that released around the same time. I didn't care much about the GPS factor as I almost always have my phone on me and the Garmin Connect app connects to Strava, which maps your runs anyways. Where this device really shines is that it is a fitness tracker. That's it. Nothing more, nothing less, but it does a very good job at doing just that, being a fitness tracker. It's extremely slim form factor makes it easy to forget that you even have it on. The battery life is awesome as well (I have yet to get close to empty, but I do take it off daily [not always] when I shower) and I've had this product for almost a month now! So A+ for design and battery life so far. In term's of usefulness, accuracy and metrics. This device comes with all the advanced sensors except for GPS as mentioned above, which may be a deal breaker for some. In terms of tracking heart rate, it has proven to be very accurate so far for myself though I've read certain variations if doing overhead activities (which makes sense because the blood is flowing away from your extremities here...) and something that I find acceptable. The HR tracker is all-day and I haven't looked for a way to turn it off, since I like continuous readings. This device can also be configured to detect when you are exercising based on your heart rate zones, which are automatically set based on your body dimensions and changed as your work out. This device also tracks your sleep extremely well and one of the most awesome features is the "Body Battery" tracker, which uses various data points to determine if you are exhausting your body and should rest/refuel, or if you have enough energy and are good to go. I have found this to be extremely accurate across various situations. Similarly to Fitbit, the Vivosmart 4 also checks your sp0(2) levels, or oxygen saturation levels. Many people might not care, but fitness junkies (and well, everyone) should, as it is a indicator of how efficient the cardiovascular and respiratory system are working. In summary, I love this device. I was choosing between this and the Fitbit Charge 3 as mentioned, but saw many and personally seen too much variation in HR readings from Fitbit devices. If HR cannot be accurately measured, it would alter all the other "metrics" that Fitbit claims to be accurately calculating. The Vivosmart 4 wins with being a pure fitness tracker (I rarely look at it or interact with it, which I think is the point), form factor, and overall price.

I am a non-techie who's well over 50. I reluctantly gave up my fit bit zip because it didn't support my new Samsung smartphone. In addition to step tracking, I wanted to see heart rate and was intrigued with the sleep and stress functions and hoped to have an alarm function for when I was travelling. I looked at lots of options and decided on the vivosmart 4. I have used it now for just over a month, tracking everything from dog walks to a strenuous hike up 2500+ feet elevation to a NH mountain top and down again. The step tracking is great, the heartrate tracking and stair flight counts pretty good, the sleep stuff interesting, and the other functionalities not of much value to me. T really like the multiple day battery charge and the waterproof design (including swims in the ocean surf). Some of the icons have taken some time to understand. Overall, I am happy with my purchase and don't find the quick recharging required every few days to be much hassle (my concern, coming from the several month long battery life Fit Bit Zip).

The sleep tracking is fantastic! Love the O2 tracking and the details provided by the pulse sensor, use the “body battery”to better understand when I’m tired and stressed. Helps be recognize when I should be taking it easy or working on getting a better nights sleep. Supper sleek design and battery lasts 5+ days, small profile works great on wrist with dress shirts. Only two down sides are that the vibration for smart alerts is weak and clearing them on your wrist doeasn’t clear them on your phone. Highly recommend!