I picked up the black one today to replace my Fitbit blaze. I had the original Galaxy gear and needles to say tizen has dramatically improved. Navigating the watch is easy and incredibly fast.
The build quality is excellent. The case is solid and has a nice weight to it. Rotating the dial gives a satisfying and addictive click you can hear and feel. The screen is of course outstanding as you'd expect on any Samsung device. The band is comfortable and feels nice. At 20mm I knew it was going to be smaller than I was used to, but I'm addition it tapers down on the underside of your wrist where it becomes much too skinny for my taste. Replacement bands will be ordered once I finish this post.
I agree with the above post about slow charging time, and I'm a little concerned about the battery. I'll be going with the AOD and custom faces, so I'm sure that won't help. Speaking of custom faces, it's a must as I've again the list above nailed it, the preloaded faces aren't great. I'm using facer currently and it's ok. The app on my Note 8 crashed a whole lot.
I'm looking forward to adding some music and going for a run without my phone. I'll update more as time goes on