I can say it's crap and I'd couple that by saying that the people that love it have no idea what "quality" is...... (or don't care if they're being sold a bill of goods)
Seriously..... there is NO mathematical formula or magic chip that can accurately guess what image would exist (or set of images) between 2 "real" frames of video. No way! So to pretend that any method that claims to do this can do this with any accuracy is lunacy.
As an owner of one of the plasmas that you refer to that have the 'judder canceller', I gotta both agree and disagree.
I agree that it affects the 'quality' of what you're watching, depending on the source.
When I first got the tv, I tried the different levels of judder cancellation on a few different blu-rays all excited about what tricks my new bit of kit could do.
When you turn this feature on while watching a typical movie shot on film, it immediately causes the movie to look like it wasn't shot on film. It makes it look like your typical daytime soap opera. Which is also the reason the term 'soap effect' has become common lingo when reffering to it in reviews and forums all over the place.
Whether it's better or worse is subjective. I think it ruins a movie. But I don't know if that's only because my brain has been trained since my first ever movie, that a movie shot on film and running at X frames a second should look like Y.
It's probably more that it's simply different to what I'm used to, and therefore doesn't feel right. When I see Pacino, or De niro doin their best.. I don't want it too look like they're doin it on Bold & Beautiful. It even affects how you perceive their acting. I mean... it looks like cheaper shows, and therefore you almost think the acting aint as good. Very strange.
However... put on a doco (like Baraka for example, or any IMAX movie) and turn it on, and it can actually be amazing. Whether they're shot on film doesn't matter as much for some reason. Because of the content I guess.
Anyway... in Baraka for example... early on where there's a sweeping shot of some volcanic mountains, without it on, you get what you get whenever the camera moves too quickly in a film. A choppy image.
Turn it on... and it's quite startling how that choppy image is now completely smooth.
Look... I don't know the algorithm used. I wouldn't have a clue as to how they do it. But I know they can, and do. They figured out the world wasn't flat, invented the wheel, flight, put man on the moon... and we got electricity, and computers and 3dtvs and all kinds of out there stuff. And I don't know how they do any of that either. So I'm sure some cats in lab coats who are way smarter than me can figure out how to make pictures on those same screens smoother.
They'll undoubtedly do it better and better as the tech improves in these displays, as they always do.
But right now, the tech is there to do it.... to your liking or disliking. And the proof is because you can go turn it on most recent tvs right now. And it works.
Actually, the concept doesn't seem that crazy to me. If I handed you one of those old school page-flipping cartoons. And left a couple of pages blank between a few cartoons. And asked you to draw the missing in between cartoons (and you were a half decent cartoonist!) you could probably figure it out. I imagine a computer or chip or algorithm designed to do that particular task could do it infintely better.
I'm completely simplifying what we're talking about here, i know.
But why is it so foreign a concept that these tvs are able to 'fill in the blanks' to some degree? It might not be what's actually in between the frames, as there technically isn't anything in between the frames.
But from where I'm sitting, it's a hell of an impressive guess.