So has LG managed to deliver on its promise of direct LED quality within an edge-LED type of design?
First impressions suggest very much that it has. For a start, the image is remarkably bright for such a slender screen. In fact, the amount of light it kicks out almost seems to go against the laws of physics.
Crucially, though, the light seems impressively even right across the full 55 inches of the screen during bright scenes, with no obvious hot spots. The brightness isn't over-egged either, with peak whites, such as those of a typical Wimbledon tennis outfit, looking crisp and clean, but never overly bleached.
Even better, the light drives an excellent palette. The range of colours achieved is truly exceptional, giving pictures a fabulously dynamic look. But even better is the finesse with which the 55LX9900 uses that range, producing superbly stripe-free and patch-free tonal blends that work wonders on making notoriously tricky content like skin tones and football pitches look totally realistic.
The combination of richness and naturalism appears to be a welcome by-product of using direct LED lighting, and it's a benefit LG has made the most of.
Also playing a substantial role in the sort of dynamism the 55LX9900 achieves is its contrast, which achieves impressive black levels to counterpoint those vibrant colours.
For anyone perhaps worrying here that the sort of aggressive colour approach we've been talking about might not be to their taste, fear not. For while we found ourselves generally unable to resist leaving the picture looking exuberantly dynamic, there's more than enough flexibility in the 55LX9900's picture tools to enable you to tone things down radically. Something the Cinema picture preset does at the press of a single button, in fact.
With many TVs we would find ourselves having to go for a more muted approach than we preferred with the 55LX9900 in order to keep noise levels in check, especially on a screen as large as this. But as testament to the quality of the processing LG has put together for this TV, noise levels hardly increase at all until you push the brightness and contrast settings to unrealistically high levels.
It's often the case that images that suppress video noise well tend to look a bit soft. But while again the tools are there to soften pictures if that suits your tastes, they can also look extremely sharp and crisp with HD. And you appreciate the detailing all the more on account of the sheer acreage of screen the TV carries. Just make sure you don't leave the edge enhancer circuit set to 'high', though, for that can start to make edges look rather overstated.
Perfection in motion
Yet more good news finds the LG 55LX9900 handling motion impressively. For while the TruMotion processing does a fine job of suppressing both judder and LCD's motion blur problems, it does so without generating many unwanted processing side effects beyond a sporadic and momentary horizontal glitch when watching 1080p/24 Blu-rays.
So far, we've been talking about the 55LX9900's 2D performance. But you're doubtless champing at the bit to hear how this monster set handles 3D. And the answer is: great in many ways, but with one irritating flaw.
The good news concerns the striking brightness and vivid colour saturations the set retains even after you've perched the 3D glasses on your nose. Inevitably, there's some reduction in the image's brightness, and whites tend to turn creamier in tone. But there's certainly nothing like the large reduction in brightness noted with Panasonic's plasma 3D TVs.
This helps 3D HD pictures look impressively detailed and crisp, even in dark image areas. The excellent motion processing the 55LX9900 carries also makes its presence felt with 3D material, delivering 3D action sequences with expert fluidity and clarity, and again without generating distracting side effects.
So, what's the catch? Crosstalk noise. For as with Samsung's C7000 and C8000 3D TVs, the 55LX9900 suffers quite badly at times with this 3D issue, where parts of the picture can appear with ghostly echoes of themselves to the left and right of their 'real' position.
At its worst – as in, when you can see it on the main subject of an image, rather than on background content where it more commonly manifests itself – this can be seriously distracting. Not to mention straining on your eyes, as they try to 'refocus out' the ghosting bits.
The key thing about this is that Panasonic's plasma 3D TVs, with their much faster response times, suffer far less from crosstalk than the 55LX9900 or Samsung's 3D TVs.
One other small point about the 55LX9900's 3D pictures is that the sense of depth they create doesn't seem quite as profound as it does on the Samsung and Panasonic models. This isn't necessarily a bad thing, though, for it arguably makes particularly deep 3D content easier on the eye and more natural, crosstalk problems notwithstanding.
Before we wrap up the 55LX9900's picture assessment, we've got a couple of issues to clear up concerning the locally dimmed LEDs. The first is that, although you're given the option to turn the local dimming off, you really have to leave it on all the time.
For if you don't, the set's black level response reduces dramatically, leaving dark scenes looking awash with grey, and colour tones less credible.
With the local dimming active, though, we noticed some very slight haloing effects around extremely bright objects when they appear against mostly dark backgrounds. This becomes quite extreme if you have to watch the TV from much of an angle.
But provided you watch from pretty much straight on and don't leave the image's brightness settings too high, haloing shouldn't be considered a major issue.