The Samsung Gear S3 is actually available in two models, Gear S3 Classic and Gear S3 Frontier, there is no difference in functionality of the two models. I got S3 Classic to write a review.
Samsun Gear S3 is compatible with any 22mm watch strap easily customizable. Gear S3 comes with a built-in speaker, so you can make and receive phone calls though you look some kind of undercover agent while doing that.
What I like the most about S3 Gear is its sensors that make it more like a sports watch. It includes accelerometer, barometer, altimeter and GPS, then there is an optical heart rate monitor on the back.
The Samsung S3 Gear AMOLED display is the best feature of this watch. AMOLED touch screen display, Gorilla glass that provides damage resistance as well as reduce surface reflection to your watch really pays off and justify its worth.
Fantastic fitness features
Smart software that makes sense on your wrist
Lack of apps at launch
Bit on the big side