I've been using this monitor since August. It's been great so far. Amazing picture quality in games, and great framerates with the 144hz. Also looks solid on videos and internet browsing. I could write a longer review about all that, but that isn't the point of this review.
A couple of days ago (Mid January 2019) I got a graphics card update for my Nvidia gtx 1080. After the update a notification popped up that my monitor was G-Sync compatible and that I could activate it in Nvidia control panel. Sure enough it was now G-Sync compatible and even indicated in game that G-Sync was activated when I had the indicator toggled on. So this monitor is advertised as Free sync/Adaptive sync, but apparently also is now magically G-Sync compatible as well. They should probably change their product title.
*Edit June 2019* Looks like Amazon has changed the description of this product to reflect that the monitor is in fact G-sync compatible after the GTX driver update back in January. Been almost a year since I've gotten it, and still very happy with my purchase.