The product is really a great invention by Google. A WiFi router is required to use this device.
Pros: Installation and setup is very easy. Just follow instructions displayed on the screen.Supported apps works very well with the device e.g YouTube.It doesn’t block your phone or laptop. You can operate them while watching videos on TV.
Cons: Screen mirroring from laptop to TV has a second lag whereas screen mirroring using HDMI cable has zero lag.Casting local videos from laptop to TV is not smooth. The video stops every few seconds to buffer the video.
Solution - You need to add Video Stream extension to your Google Chrome on laptop. If you still face issues with buffering then go to Video Stream settings and enable Buffering Fixes ( Beta) .It solved problem for me as it compresses video on laptop and transfers over WiFi.