First off... these cardz aren't really trading cards as they might want you to believe.  They come in a complete, predictable pack of four - Aki, Gray, Sid, and Hein.  If you get one, then, chances are, you have gotten the rest with it.  The only exception is the Ryan card, which was a promotional item sent out with ToyFaire magazine.  Something to do with Palisades, I imagine, but anyway....

The cardz are about the size of a typical trading card, only... made of tough plastic and with a hole in the middle.  On the face, they have an image of a character, and on the back there is an inset CD image.  You insert it into a CD tray (Sorry, folks with slots) and plug your ears.  Depending on your surroundings and the current air/sound flow, you will be treated to a pitch and tone somewhere between a hair dryer and a vacuum cleaner.  Or perhaps this is just me....

At startup, a FF:TSW Trailer plays.  You may skip this on the typical cardz, but for the promotional Ryan card you will sit through it no matter your opinion.  Or, again, perhaps this is just me.  Anyhow, after the trailer, you are staring at your starting screen.  The interaction is fun, where you select one of the cubes on the top left and drop it into the orange square.

Freudian, I know.

Depending upon your choice of cube, you are invited to study vehicles and objects of interest; view a characters' statistic; play with a slider puzzle (coincidence or callback to the first Final Fantasy game, I imagine...); listen to clips from the soundtrack; view an image  gallery; and so forth.  You may also find other little things to play with within the main sections if you explore.

They are a bit redundant, but they are entertaining.  You can generally find them cheap if you can use eBay.  The Ryan card is, again, the exception - simply for a lack of them being sold.  I do see them now and again, and they rarely go for too much, but it seems to be something to actively watch for if you want to find it.