One unusual thing about most Vizio TVs this year is that they don't use the company's old VIA Internet Plus smart TV platform. Instead, they rely on Google Cast, a cloud-based technology, for streaming movies and getting other internet content. (Vizio's smart TVs also lack built-in tuners for over-the-air reception, but that's another topic.)

To access a Google Cast TV's internet-based services, such as streaming movies, you need to use a mobile app loaded on a smartphone or tablet. Vizio's higher-end P-series sets and M-series models all come with a 6-inch Android tablet loaded with Vizio's SmartCast app for this purpose. But other Google Cast TVs—from Magnavox, Philips, Polaroid, and Westinghouse, as well as E-series sets from Vizio—are generally relying on consumers to supply their own mobile devices.

The TVs come with rudimentary remote controls, but they can only be used for basic functions such as changing channels, adjusting the volume, and switching inputs. 

Most people shopping for a smart TV probably own a smartphone. And a Philips spokeperson said that an advantage of Google Cast is that consumers can use their existing devices, which are already configured with their Google usernames and passwords, "Offering an independent tablet conflicts with that benefit since the consumer will need to install and configure all of the new apps on their TV tablet," he said. (Vizio did not supply a comment in time for publication.)

However, we're not so sure this benefits consumers. Most of us carry our phones when we leave home, or even move from one room to another. That means either everyone in the household will have to load the app on his or her phone, or you'll end up dedicating a separate tablet to this purpose.

Television manufacturers presumably like the idea of reducing costs by letting Google maintain the platform, and by including simpler remote controls with their products. And Google Cast offers some benefits to consumers—it offers access to lots of apps, and it's likely be updated more regularly than proprietary smart TV platforms. However, we're not big fans of companies shipping televisions that won't work fully right out of the box. 

If you enjoy Google Cast and you're looking for a new TV, there are better options. A number of TVs with built-in smart TV platforms also support casting. And if a particular TV doesn't do that, you can always add a $35 Chromecast media player, which has Google Cast baked in.

Either of these choices will let you access everything Google Cast offers, while still streaming content even if your spouse leaves the house with his smartphone.