Greetings:
First post here (hello all). A bit of a personal intro too (re: my own S3D experience so far).
FWIW, I discovered your site (and forums) by way of a link put up in the "Nvidia 3D forum" by one of your members a few days ago, after the Nvidia 3D announcement at CES 2009.
Don't remember offhand who it was who steered me here, but I certainly thank you for the link. It's always nice to find "fellow believers," as regards anything....
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To the question: I like S3D mostly because of the sheer immersion factor. It's very, very good when you get it configured right (and I'm convinced, too, that it can be made "nearly perfect" if tweaked just right).
Caveats: From my perspective, to be reasonably immersive, the stereo image must be pretty near lifesize (or at least somewhat close to lifesize).
I have been using S3D, off and on, for several years now, but it was only when I began to use it in concert with a DLP projector (and true lifesize image) that it really began to "pop" for me.
My first setup was using a Mitsubishi 2060 20" CRT monitor with I-Art 3D glasses (two pair, one wireless). Good...and certainly eyecatching...but not great with the sim-racing (driving) apps I most wanted to use it with. I was able to use the glasses at 120Hz (great monitor, btw, and one which had a "superbright" feature too which was obviously quite helpful in combatting the overall loss in brightness due to strobing of the glasses).
The "believeability" issue, for me, lay with the overall size of the image. Since the best I could generally do was something like 1/4th-1/3rd a lifesize FOV (and image), it never really felt like I was driving a full size car, but rather something more like a very small go-kart.
Things took a turn for the better a couple years back when a family member bought a NEC LT180 DLP (1024x768) projector...and I was able to borrow it for some extended testing.
That projector throws a much larger image than most at a shorter range...which meant I was able to mount it (temporarily) just over and behind my head and project the image onto a screen just only 24-30" ahead of me (right behind my race-cockpit's steering wheel). Moreover, because the simulation I currently drive ("rFactor." Go to "rFactor.net" for more info) allows FOV (field of view) adjustments I was finally able to tweak things so that I was seeing:
A) A horizon located AT the true horizon, and not above it--my legs protrude, quite literally THROUGH my viewscreen--a significant portion of the image is projected below the horizon, and into the lower left and lower right corners of my screen (I'm hypersensitive to this "true horizon," for whatever reason, so for me, having it exactly level to the "height" of my eyes is very important );
B) An overall size of the relative screen elements that is very, very close indeed to reality, and;
C) An overall level of brightness that (mostly) offset the negative effect of using the shutterglasses.
It wasn't perfect--the best the projector will do (@1024x768) is 85Hz, but that still gave me 42Hz per eye, which was certainly usable for me.
There were color-shimmer issues (due the the speed of the colorwheel (I think) vs, the strobe rate of the glasses), but they were certainly not show-stoppers.
I very much enjoyed using the rig, and was able to drive for many hours at a stretch without headaches or other adverse vision effects, so I became a true convert to the technology (instead of merely a "near believer" (as when using the CRT).
I hope to borrow the projector again in the very near future to repeat the experiments once again (blown bulb replacement is on it's way in the mail), so if anyone should want more detail (settings, for example) I might be able to provide them.
In the meantime, and once again: "Hello to all." I hope I can contribute something useful as time goes on.
I certainly do think lifesize S3D is THE way to go, if you can manage to set it up.
k