The Now TV app on the ATV 4 is probably the worst video streaming app I've ever seen. It's not only eye wateringly ugly, but lacks even the most rudimentary of stock features, such as a My List equivalent, last watched list, etc. It's abysmal. There's a huge thread on the Now TV message board where people are asking when Sky are going to fix it, but it's pretty clear that they never will. It's simply a port of their already terrible and very basic ATV 3 app which hasn't been updated in years.
Now TV is a lot better on every other platform, try it on a Roku, PS4, Xbox One, LG Smart TV etc. Light years ahead, but sadly still stuck with the same over compressed 720p video with 2.0 stereo sound. It's a long, long way from a high end experience. Netflix and Amazon make it look like a real amateur hour effort, but Sky have a few big exclusives of course, such as Game of Thrones.