There are some games that you really ought to play under emulation only, and Shadow of the Colossus is going to be one of those. It's a beautiful, interesting game held back by the terrible, terrible PS2 rendering chip. Depending on your hardware, if you haven't played it already, you might even be best off emulating it now.
It was kind of surprising to me how bad the texture handling actually was. I skipped the PS2 when it was current, and only really got to sit down with one when I started using Belle's for Guitar Hero. I had bought a second-hand Dreamcast instead, or played a lot of older PC titles on my low-budget tower (calling it 'hand-built' implies, I think, a level of craftsmanship that wasn't present). Both of those had their issues, but they were capable of handling basic texture filtering, and character models didn't shake like a pair of cheap maracas, neither of which seems to have been a priority for Sony's Emotion Engine designers.
Normally, I'm not a graphics snob kind of guy. I enjoy Wii games for what they are, and I've never owned a computer capable of running new games at their top detail levels. I think Link's Awakening was one of the top two Zelda games, even in four shades of Gameboy Green. But my first reaction to SotC when I finally got around to firing it up this week was "wait, is there a way to turn off the Awful, Shimmery Moiré Filter?" Under the Playstation's dubious rendering context, anything more than five feet away from the camera becomes a shifting, grainy distraction. The development team has clearly tried to integrate this into the art style--I think the elaborate hair and stone textures, not to mention the blown-out bloom and grain filters, are a direct result of accepting the platform's limitations--but it doesn't really work. Not right away, at least, and not without interruption. And these ambitious effects come at a cost--even on native hardware, the game's framerate is notoriously unstable.
Unfortunately, the elaborate tricks used to push the PS2 as far as it can go mean that Shadow of the Colossus is a punishing feat for emulators. While recent PC hardware is easily capable of handling titles like the Final Fantasy games, SotC barely manages more than 10 frames a second on my 2007-era laptop. But it's a tantalizing slideshow: even at its native resolution, without the shaky landscape textures and shifty light bloom, you can really see just how beautifully-designed this game was. If I had a little more CPU to throw at it, I'd love to play it there instead of on Sony's temperamental black box.
As a long-time PC gamer, I've been using emulation for years, and this isn't the first time that the experience has been better on a virtual machine. If nothing else, it means freedom from the idiotic "save point" systems, particularly in console RPGs. I've always preferred the ergonomics of a keyboard or my favorite PC gamepad to whatever weirdness the original manufacturer has invented for their input device (Dreamcast, I'm specifically looking at you and your RSI-triggering monstrosity of a controller).
And more importantly, emulation has historically allowed the technical limitations of the day to be upgraded behind the scenes--from removing the flicker of NES sprite rendering (then restoring it, for the diehards) to the addition of mip-mapping and texture filtering on the PS2. My favorite, of course, is the gorgeous pixel-art enhancement of the Super 2xSaI algorithm. If you ever forget how well-crafted the peak of 16-bit gaming could be, play the first few rainy minutes of A Link To The Past in high resolution through a modern emulator. I think if you look at something like Pixeljunk Shooter, it's an unmistakeable tribute not just to 2D gaming, but to the advances that were first made in emulation, now brought back into the fold.
Which brings us back to Shadow of the Colossus and the poor, palsied PS2. As one of those games that'll get name-checked for years to come, and with the PS3 dropping backwards compatibility, emulation may end up a real blessing in disguise for SotC--new players will get the benefit of its stunning art and sound design, but without the crappy rendering. It's just too bad it takes such a monster of a system--a colossus, if you will--to do it, but that problem will solve itself over time. To be honest, I'm almost a little envious.