To call this TV "real-world 4k" is probably a step too far, but the UE55JU6400 is resolutely an entry-level, next-gen TV for those who rate resolution over everything else.
As such, it's a good effort, though that's thanks just as much to its slick Smart Hub interface and apps as those extra pixels.
Ultra-HD 4k detail pops on the UE55JU6400 when watched head-on, with colours impressively nuanced and the picture always clean and full of depth. HD channels look superb, though in terms of upscaling, Blu-ray discs are unbeatable; there's no doubt that the UE55JU6400 is up for the 4k future.
Samsung's new Tizen-driven OS for its Smart Hub is a huge success, though so far that's down solely to its reliance on a pop-up bar across the bottom of the screen. Apps such as YouTube, Netflix and Amazon Instant are all here, and everything works quickly.
It does its best, but the UE55JU6400 can't prevent standard-definition TV channels and DVDs from looking soft and noisy, while contrast and black levels fade from all qualities of video when the UE55JU6400 is watched from the wings.
While Smart Hub works fine, the TV's built-in menus tend to be sticky and slow, which suggests that the quad-core processor has a lot on its plate.
Annoyingly, the Screen Mirroring option for smartphones, which is flagged in the permanent onscreen menus for Smart Hub, doesn't apply to non-Samsung models.
Having just spent big money, that's a kick in the teeth. We could say the same about 3D. Its omission is surprising, though I'm not sure how many people will care about the format's demise. Sat-fans should also know that there's no Freesat HD tuner.
This is a fine example of a 55-inch 4k TV, and it's only a small price-cut from being good value, too. Ultra HD 4k TVs will soon be everywhere – your next TV will definitely have a 3,840 x 2,160 resolution – and it's good to see some decent 4k upscaling already in place.
Awesome 4k detail and colours from native 4k sources are accompanied by a pristine treatment of all HD content, though standard-definition material can look noisy. Technically, its biggest problem is its tight viewing angle, though without Freesat HD or 3D compatibility, the UE55JU6400 won't be for everyone.
Save a few quid by going for the Samsung UE55HU7500, which was out last year and remains on shop shelves – for now. It's got 3D compatibility, too. So has the great-value Sony 55X850B, which is being discounted now.