Google claims that the Ultra is far faster than earlier Chromecasts. It should load videos 1.8 times faster than the second-generation Chromecast.
It can do this due to more advanced hardware. Besides a faster processor, it comes with HDMI, USB-C, and Ethernet ports. The last one is important, because if you're still using 802.11g Wi-Fi, or your TV is a long way off from your 802.11n Wi-Fi router, you'll need an Ethernet connection to stream 4K video.
The new Chromecast also includes 802.11ac Wi-Fi. If you're watching 4K, you'll want 802.11ac.
The device supports video streaming on the following operating systems: Android 4.1 and higher, iOS 8 and higher, Mac OS X 10.9 and higher, and Windows 7 and higher. Based on my experience with earlier models, it will also work fine with Chromebooks and Linux desktops.
What it will deliver, besides faster performance, is 4K video (aka Ultra TV). Unless you're a video professional, that means you'll be watching a video with a pixel resolution of 3840x2160. That's four times the resolution of HDTV's best 1080p resolution.
It also supports HDR. To my eye, and I'm not the only one who sees it that way, HDR makes video more enjoyable to watch than 4K does. It does so by expanding your TV's contrast ratio and color palette to offer a more realistic, enjoyable display.
To watch any of this, you'll require several other technologies. First, you need a high-speed internet connection. The absolute minimum bandwidth you need for 4K is 15Mbps. Netflix recommends 25Mbps for 4K, and it's not wrong.
So, why should you bother? Well, if you have the net connectivity and the TV that can support it, the Chromecast Ultra at $69 offers the cheapest way to stream 4K video.
In addition, the Chromecast Ultra is an essential part of Google Assistant. With the help of Google's new Google Home voice-activated, smart home virtual assistant hub, you'll be able to not only control your TV-viewing with your voice, you'll be able to use a personalized Google on your TV.
For such a small device, I foresee a big impact on not just how you watch TV, but how you live with technology in your home.