It was a hard decision to buy either the Fenix or the Vivoactive. But, I have a general tendency to over-buy technology. I've never been disappointed over buying tech but I find I never use half of the capabilities. But when I looked at buying the more elegant looking Fenix the cost compared to the Vivoactive was a big number. I'm happy to say the Vivoactive meets all my technology requirements and I'm still not using full functionality. I'm an avid road cyclist and use my Vivoactive to track my rides. My only complaint is that I ride with an Edge 1030 and Garmin Connect does not synchronize the data between the Edge and Vivoactive. Instead it creates a duplicate ride. So, I have to turn off the Edge automatic upload and use the Vivoactive as a backup. When I finish a ride I turn on the Edge auto upload, sync, make sure everything is uploaded, then delete without saving the ride on my Vivoactive.
The 4s model is as big as I would want. Feels solid and well made, has survived a few bumps with no marks. All the features work as expected. Mostly use it as sleep tracker, but have explored the other apps and am liking the fitness applications a lot. Factory strap fits my 7-3/4" wrist with 1 notch to spare. I got a Nick Mankey Designs elastic wrist strap for it (18mm) and is very comfortable to wear now.
I really like the watch and how it works, and how it tracks heart rate, VO2 max, and pulse ox. Sometimes the heart rate measures are a bit off, becuase it takes a while for them to "catch up" when there is a spike in heart rate. Also the hydration tracking app has a lot of glitches.
Ok, so I'm not a super techy person and I bought this at my super techy husband's recommendation.
I absolutely love this watch!
I love to see how well I slept (or not), the steps and stairs I take in a day, water consumed, cals burned for specific exercises, HR zones, calendar events, texts, messenger and I can control my Spotify playlist!, the list goes on.....
I highly recommend this watch for anyone really.