TV is the worst thing Apple makes. It's glitchy, inconsistent, confusing, and just doesn't work most of the time I try it. Old units, new units, doesn't matter, they're all irritating to use.
My $40 Roku has been utterly flawless, still allows me to AirPlay (and Android friends can cast), and oh yeah it's $40.
The only app that I haven't been able to get to work right on said Roku is, surprise surprise, the Apple TV app. No sound when attempting to play movies. Never been able to get it to work.
It isn’t that bad, but it isn’t good either. A comprehensive redesign is needed. I doubt this article points at one though.