Ive embarked on a fitness drive and purchased a Vivofit 4 Fitness tracker. I already have the free Runkeeper app on my phone but thought it handy to have something watch-sized. Just did my first walk with the Vivofit and ran Runkeeper at the same time to compare:

Vivofit 4: 2.51km, 126 cal
Runkeeper app: 3.19km 205 cal (includes elevations etc)

Given the significant difference I then drove the route- Car Odometer: 3.1km

My 1st wearable so I bought relatively cheap. Still over priced.
Accuracy verges on useless apart from gentle motivation.
App and data is basic and loses value after a few weeks.
BUY, main gripe is main reason I bought it was advertised long battery life. I was shocked to find it died after less than 5 months (product description says 1yr+). When I contacted Garmin I was literally to.d it was my problem and they were not interested.
Would advise against this product and based on customer service also any Garmin product

Used all the vivofits and been happy to see my steps and activity build to tremendous levels. Thanks Garmin for providing those statistics for which it has accurately provided me in all this time. Now while undertaking my daily 8-10km powerwalk, see this device ripping me off anywhere from 25 to 75%. Evidence can be especially seen when viewing each activity's pace map which can be viewed in the devices app. Just seems to stop and not keep up. Time now to ditch Garmin and look elsewhere.

As per other reviews, my fourth replacement has just failed. Utter rubbish.
The screen freezes each time and stays on either the clock or Date.
The last replacement I got I said I wouldn’t accept another replacement and I won’t. I also won’t be buying a Garmin again.
This one lasted only 2 months, the ones before at least lasted 6 months or more

The Vivofit 4 is a great fitness tracker, if you’re happy to just use the band for its battery life. I’ve had 2 of these in the past and they worked perfectly, until I had the batteries replaced. I was aware, both times, that they would no longer be waterproof, and I was vigilant about never getting them near water. But you just can’t help sweating while using them. And only a few short weeks after replacing their batteries, they just stopped working. It’s time for me to look at other options.

The band of my wife's earlier Vivofit failed after a few months, I bought replacement bands, plural, the bands are grossly over-priced rubbish and would have been cheaper in a bulk purchase if the device had lasted, but the device soon failed. I was silly enough to buy a Vivofit 4 to replace it, its band failed after just a few months, and it was different from the replacements on hand from the previous Vivofit so I bought a new band, then the device failed a few days short of the 12 month warrantee, batteries flat. Replacement batteries were n...

What a piece of junk!!!! It doesn't sync properly ever, and all it does is count your steps. I basically use it as a watch. Can get my money back?

My daughter is onto her 3rd Vivofit 4; soon to be 4th since Christmas 2019 as each one works for month or so then starts to lose time. If you put up with that for awhile then something else will go - the screen fails or something else.

I purchased this watch after having the vivofit 2 for almost 3 years. Was excited to upgrade after having such great luck from the vivo2. Since Christmas I have had to send back my vivo 4, 4 times. The watch will last about 7 weeks and then freeze up and stop working. Garmin was great about sending me a replacement each time after I paid to ship it off. After the 4th time of the watch messing up on me, that right, 4 different watches!!!! I am done with it. Time to move on to a better quality watch, clearly garmin isnt it

Bought for my daughter for Christmas 2018. First and only time it was taken swimming in 0.5m of water for 5 minutes last weekend, water ingress found where water was on the batteries causing it to show the low battery black triangle symbol and the button no longer functioning correctly. Replaced it after some pushing when the retailer didn't initially want to replace it, wanted to refund and upsell a more expensive model. Thankfully they agreed to replace. For something that is supposed to be waterproof but unable to withstand a swim for 5 minutes must have been a major manufacturing fault, and/or I'm expecting to find this same problem down the track.

Beware of heavily discounted products online.

I received an offer by way of BUPA for the unit, it was $90. Original price would have been $200+. I was suspect from the beginning that I was not getting a NEW item but most likely a Refurbished unit. So, it was no surprise when it only worked half the time.

In Garmin's favor though, they did take it back.
At the time of this writing however the refund has yet to eventuate, I trust however that it will.