I've used Chat since the launch and I just hate it. Having it built into Gmail makes it so cumbersome. Having a stand alone app (like Hangouts) makes access so much easier. But the worst part of Chat is that I don't get notifications on my Pixel when someone messages me. I have missed countless messages because of this. Edited to add: to clarify, notifications are sporadic and inconsistent, not completely absent. Also, notifcation settings are turned on as recommended.