I've been testing my new "4" for a few days now and find it to be a nice upgrade from my Avov 2 box. Although I don't have a 4k television, the picture quality is very good. I look forward to the surround sound issues being fixed, as I have built a home theater room in my new home and will use the box's S PDIF connection to an A/V receiver, a 7.2 speaker system, and an Epson projector. I've had no issues getting KODI running well. I was hoping to see some improvement with freezing of Rocket IPTV, but it's still an occasional problem. I'll test a VPN service to see if that might help.
Like others, I find the opening chime on power up to be very annoying, but understand a fix will be coming. For now, I turn off my TV, turn on the 4K box, and after a few seconds turn on the TV. I also hope they will silence volume changes.
All in all, the box is an improvement and I think I'll be very happy with it.