the thing that makes these SD cards so special is that they have built in wi-fi functionality- using an app called shuttersnitch on the ipad you can view pictures directly on the big retina displayed iPad! it's pretty quick to transfer as long as you set it to record RAW to the card and transfer jpeg to the iPad (takes about 2 seconds to transfer)
Because the cards have built in wi-fi they don't need to use any other network, so you can use these in the middle of nowhere (unlike the mk1 versions which needed a wireless network to join), this is much handier and makes the eye-fi cards a serious solution for wireless photography.
They are pretty easy to use, just set the app to conenct to the eye fi's network and that's it, you change all the settings on the card by plugging it in to a computer and using the supplied software
8gb isn't the biggest card in the world, but as these are already quite expensive it's unlikely you'd use these as regular SD cards- use cheap SD cards in 16/32gb when you need the space, and use the eye-fi cards when you need the wireless ability.