The first thing that hits you when watching a full HD 3D Blu-ray is how amazingly detailed pictures look. Every last tiny pixel of full HD detail - such as the minute shiny 'panels' in the aliens' clothes in Monsters Vs Aliens - is shown with extreme accuracy and not a trace of noise. In fact, they're arguably the sharpest 3D pictures seen on any TV to date and help the set deliver a really impressive sense of depth to 3D shots.
Provided you set the PS51D6900 to its Dynamic picture preset when watching 3D, it also delivers impressively rich, dynamic and believable colours, and retains a decent amount of brightness too. Certainly, there's no sign of the hollow look that affected dark areas on Samsung previous generation of plasmas.
The only minor problem with the PS51D6900's 3D performance is that it suffers a little more from crosstalk ghosting noise than Panasonic's plasmas.
Happily, though, this is usually restricted to what you might call 'internal' crosstalk, where you can only see the ghosting within relatively dark objects. For instance, during the Golden Gate Bridge sequence of Monsters Vs Aliens, while the struts and cables appear more or less crosstalk-free against the blue sky, internal reflections on the widest of the struts do ghost a little.
Motion occasionally looks a touch uncomfortable in 3D mode too, with slight judder affecting backgrounds during camera pans or tracking shots. It is a minor niggle, though, rather than a significant distraction.
One last, minor, grumble is that there is no dedicated picture preset that kicks in automatically as soon as the TV detects a 3D signal.
With 2D material, without the darkening effects of the active shutter glasses the PS51D6900 immediately suffers in comparison with Panasonic's GT30 and, especially, VT30 series by virtue of not delivering nearly the same degree of black level response. There's a slightly greyer look to dark scenes, which inevitably reduces their impact. It also marginally affects the tone of very dark colours, and there's slightly less shadow detail to be seen in very dark areas versus the latest Panasonics.
However, not being as good as Panasonic's remarkable screens when it comes to black levels does not mean that the PS51D6900 can't still deliver a very engaging performance indeed. In fact, by any other, non-Panasonic measure, black levels are very good. They certainly look deeper than those of last year's equivalent Samsung plasma model and outgun those of practically every LED/LCD TV - especially once you've taken the immaculate black level uniformity into account.
The impeccable sense of sharpness and detailing noted with 3D continues into 2D mode, too, and colours are rendered with an engaging mixture of vibrancy and naturalism. There's no doubt that Panasonic's latest G and V plasma models deliver a punchier and even more dynamic colour palette, but the PS51D6900's pictures are never less than credible.
The set's plasma technology also means you can watch the screen from a much wider viewing angle than Samsung's LCD TVs and there's no motion blur whatsoever, again thanks to the innately fast response time of plasma technology.
Also impressive is how well the set upscales standard-definition material. Samsung TVs generally perform unusually ably in this key regard, but converting a relatively grubby standard-def digital broadcast up to HD without losing significant colour accuracy and colour striping is particularly difficult on a plasma set. Yet the PS51D6900 suffers hardly at all with either issue.
Finally, the PS51D6900 appears to be a decent gaming proposition, thanks to a pleasingly low 34ms of input lag. This shouldn't be enough to contribute on any regular basis to unfair deaths in Call of Duty or missed notes on Guitar Hero.