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When it comes to living with the TX-40CX680B, the Quad Core Pro processor is a huge help, making the new Firefox OS a highly impressive smart TV hub.
Colourful and easy to customise, Firefox OS is one of the best-looking smart TV platforms of all, though it does lack content. The new interface is actually called my Home Screen 2.0, though it bears no resemblance to version 1.0 from 2014.
Much like the other major TV brands, Panasonic has abandoned the concept of having a separate smart TV homepage in favour of pop-up icons. Press the Home button on the distinctly old-fashioned remote control (save for a dedicated Netflix short-cut) and Firefox puts up a carousel of large, round icons in the middle of the screen against a transparent backdrop; everything underneath continues to play.
The first four are Live TV, Apps, Freeview Play Catch-Up and Devices, which gives one-touch access to the TV's core functions.
That's some excellent work.
Carry on through that carousel and you'll come to various icons representing recently used apps and services, such as YouTube or Netflix, before a long list of TV channels is presented. Finding BBC 1 is therefore pretty easy.
However, press the Apps button on the remote and the Firefox OS takes you to a dedicated page of apps. Unlike previous incarnations of Panasonic smart TV hubs, this page is distinctly uncluttered and contains just 14 key apps, among them Netflix, Amazon Instant, YouTube, AccuWeather, and links to the TV's internal features and services including a calendar, inputs, TV channels and a web browser provided by – you guessed it – Firefox. However, it's a fairly basic browser. Up front is a link to Panasonic's apps market, too.
Though it does lack the content and endless apps offered by Android TV, Firefox OS is by far the easiest smart TV interface to customise; anything from an app or device to a web page or a TV channel can be 'pinned' to the carousel in seconds.
Panasonic also has an ace up its sleeve. Just as Sony is about to unleash YouView to its Bravia TVs, the Viera line-up is about to get Freeview Play, which will integrate catch-up TV services the BBC, ITV, Channel 4 and Channel 5 into the core user interface.
Finally, there's Info Frame, which is activated by a long press of the Home page.
It's a completely transparent screen that gives you four options tight to each side of the screen; a TV guide, Weather, Notifications and Recommended.
Though the list of TV channels is nicely executed, it's a little long-winded to find it, while the Recommended section merely lists random videos on YouTube and Viewster; Info Frame is the least successful part of the Firefox OS.
However, since it's well hidden, most people will probably never find it.
Without Google Play, the Firefox OS doesn't compare to Android TV on content, but in terms of simplicity and customisation of basic features, Panasonic's Firefox OS remains one of the best attempts yet at smart TV.
USB sticks and network devices are supposed to appear in the Devices section of the Home page, but during our review the TX-40CX680B detected their presence but did not display an icon, leaving me no way to test digital file playback.
The TX-40CX680B's 20W speakers are impressive, with a bass boost option adding some grunt to proceedings.
However, the virtual surround mode merely increases the background noise, as does the ambient mode.
Though stronger than most TVs and more than good enough for everyday TV and some music, just as integral is the TX-40CX680B's optical digital audio output for routing sound to a home cinema or sound-bar.
Are you kidding?
Most decent Full HD 40-inchers cost about £600, so the addition of an all-new Firefox OS that's among the finest smart TV platforms of all, a talented LED panel and those 4K pixels make the TX-40CX680B a bargain at just UK£669.
With Freeview Play incoming, this TV is only going to get better value.
Jamie is a freelance tech, travel and space journalist based in the UK. He’s been writing regularly for Techradar since it was launched in 2008 and also writes regularly for Forbes, The Telegraph, the South China Morning Post, Sky & Telescope and the Sky At Night magazine as well as other Future titles T3, Digital Camera World, All About Space and Space.com. He also edits two of his own websites, TravGear.com and WhenIsTheNextEclipse.com that reflect his obsession with travel gear and solar eclipse travel. He is the author of A Stargazing Program For Beginners (Springer, 2015),