This bundle, which includes a Stadia Controller and a Chromecast Ultra, is a great way to get into Google's cloud gaming service. However, this discount is to clear out old inventory of the older Chromecast, as Google also makes a new Stadia controller bundle available.
This new bundle, priced at $99.99 USD, includes the Stadia Controller and the new Chromecast with Google TV. In addition, an available Chromecast ethernet adapter for $9.99 is highly recommended for the best cloud gaming experience.
The $99.99 price puts the bundle at a $19 discount than if you purchased the two items separately. The best part, if you are a new Stadia player looking to get into the cloud, you can purchase this bundle and get a month of Stadia Pro included; that's another $9.99 value included in the $99.99 bundle!
Both bundles are a good deal. However, I highly suggest spending the extra $20 for the newer Chromecast with Google TV bundle. It will likely last you a lot longer, and it includes extra features!