I've been wearing the Vivosmart since i got it.. looking back.. on 19th nov last year. It's great for what i want it for. That is/was to motivate my pale white arse to moving around more and getting in better shape. It soon superceded the Google Fit app on my mobile, as that is pretty rubbish really.
What was a real eye-opener for me was the social aspect, especially the motivation from others. On the Garmin website itself the social integration is basic, to say the least, but i found a group on facebook for vivofit/smart users that was brilliant. Many nice people in their 40s and 50s with roughly the same aims.
I don't bother with the 'smart' sms, tlf, etc notifications. That's what my phone is for. In fact, i don't even run the app on my phone. The vivosmart is the least obtrusive fitness band. The step counter is accurate. The sleep info (for what it's worth) is the most useful i've seen. And it syncs with all the other Garmin products.
I bought a secondhand Garmin FR910, five or six weeks after i got the vivosmart, for recording runs, and soon cycling and swimming.