Been playing with mines for about 30 min now. I'm impressed so far.
The full screen ads on the lock screen are not bad at all. And it only does full screen if you have no notifications shown, otherwise it will show your notifications over normal wallpaper and a small ad under the notifications. Amazon did a great job at not being intrusive.
The phone itself fells thick compared to my S7 edge, but it feels good. The speaker audio is pure crap, it's laughable. The headphone audio is loud and crisp. The camera takes decent photos front and back, way better than I expected. And not too bad in low light, but nothing compared to today's flagship phones.
Android feels snappy, responsive, and lean for a budget phone of this price. Haven't seen a hiccup yet. The icons are too big for my taste though. I'm hoping for root and custom rom on this phone. Plus I hate the Google search bar on the top.
I played some Amazon Prime and Youtube 720p videos on this and they look good. The display itself is bright enough for my satisfaction, and the color saturation seems minimal.
I didn't get to test my T-mobile sim, cause I can't find my nano to micro adapter. So I wasn't able to test T-mobile LTE service yet. Wifi connection is good, but no 5GHz. Bluetooth and GPS work excellent.
Can't speak on battery life yet.
The micro USB slot is pretty tight, hope that doesn't cause breakage down the line.
So far the only thing about this phone that is horrible is the speaker. It's the worst speaker I've ever experienced on a phone, EVER!!!!
But other than the speaker, this phone is worth every dime. More than meets my expectations.