I spent the last year with a Note 3 (AT&T) and Samsung Gear 2 Neo. I've had the Zenwatch 2 for three days paired to an unlocked Nexus 6 on AT&T.
I prefer the Zenwatch in every way except battery life and the battery charger. The Neo was a 2 day battery (I charged it every other night) while the Zenwatch 2 is a one day battery (I charge it every night).
It came off of the charger at 7 AM yesterday morning and at midnight it was at 14%.
Off the battery again at 7 this morning and I am at 81% at 1:20 in the afternoon.
The charging cable is too short for my tastes, and I never like having a dedicated cable that is permanently attached to the wall wart. I prefer a cradle or a way to use one of the estimated 4000 micro USB cables that I have laying around.
The interface on the Neo was **** ugly in my opinion, but it was fast and battery efficient. I much prefer the Zenwatch graphics and interface.
The only issue I have had in these first three days is that the first two mornings when I pulled the watch from the charger it said "Zenwatch Manager is not responding". I rebooted the watch and went on my way with no issues. I did not have that message this morning when I took it off of the charger.
I got the bigger of the two sizes in gunmetal with the dark blue leather band. Comfortable to wear and easy to use. There is a lot of scrolling with pretty much any wearable but you do learn shortcuts. For instance if I scroll all the way to the bottom of my notifications, instead of scrolling back up just cover the watch with your palm and it will turn off. When it comes back on you are back to the watch face.