I used to love my Rokus as the interface was clean and fast and rock solid. But with the advent of 4K and the voice search "feature", I've had nothing but problems with my Ultra.
First I was getting DCHP errors.I updated to v.9.0.0 of the firmware which solved the error but introduced blinking of the picture every few minutes ( occurs on all channels, even home screen and screensaver).
Some of the programs on Amazon Prime have severe audio sync issues (programs play fine on smart TV and Tivo apps). Also, the voice search can't seem to find ANY shows with the words "garden", "gardening", or "restore" in the title.
But the truly infuriating part is their dismal "support". The chat and phone support agents tell you to reboot the device and change the HDMI cable. When that doesn't work they tell you to NOT try and watch in 4K. Um, I bought a 4K TV and the Ultra to watch TV in 4K! Also, I have yet to get a response from ANY email support requests. They also LOVE to blame the app developers. "Don't blame us. We're just lowly hardware manufacturers."
Roku has had the opportunity to be a key player for helping users to cut the cable cord. However, their hardware, software and especially "support" is far inferior to that of the cable companies I have dealt with. With the built in apps in smart TVs, and Google and Amazon devices, Roku is becoming less and less relevant.