The UE40H6400 certainly delivers plenty of onscreen ooh-ah. Fine detail performance is excellent and the set positively radiates vibrant colour, courtesy of an effective, but ultimately mysterious, Wide Colour Enhancer Plus algorithm.
The basics are sound. Edge lighting is largely even, with no overt light pooling in the corners of the screen, and while the screen doesn't go pitch black, overall contrast is high; there's very little in the way of pixel noise either. It seems the lack of local dimming tech is not a drawback.
That said, the TV is unable to display deliberately dark scenes. During Kill Bill Volume 2, as Uma Thurman is buried alive, the backlight threshold is such that the panel switches on and off.
Traditionally, Samsung has specialised in fairly hideous presets but there have been obvious improvements made this year. Neither Standard nor Movie modes disgrace themselves, while motion handling can be excellent provided you select the right interpolation.
We found the Motion Plus Clear mode to be the most effective general-purpose setting. This retains a full 1080 lines of moving resolution and avoids inflicting noisy halos around moving objects.
Also recommended (as usual) is the Motion Plus Custom setting, with Blur Reduction set between 8-10, and Judder reduction parked on zero. Alternatively, if you want a more cinematic image, just turn Motion Plus interpolation off altogether. While there's some penalty when it comes to motion resolution, the relatively small size of this screen mitigates against the shortfall. You'll also be free of the video-style soap opera effect common to LED picture processing.
Image sharpness is best kept limited to 15. Pictures can be given a little more crispness by engaging low levels of Dynamic Contrast and turning on the Dark Tone setting. Less pleasing is LED Clear Motion, which adds overt flicker.
3D aficionados will most likely be disappointed though. The H6400, which uses Active Shutter technology, offers a rather uncomfortable 3D experience. Crosstalk is rife, with white double imaging pervading the picture. As it transpires, 3D on a 40-inch screen isn't immersive anyway, so this failing is unlikely to be a deal breaker. Two pairs of shuttering 3D glasses are supplied in the box.