I have used a few Eye-fi cards. If your camera does not have wi-fi, its a nice option.
You get free geo-tagging until they decide to stop supporting whatever card you get, but they try to get you to buy their subscription stuff.
Wifi drains battery, be warned. Especially bad if you leave the camera on while moving to a new location.
Expensive.
It is really helpful for syncing photos if you do not have a wifi camera already. If you are looking to upgrade a camera in the next year, the $99 might be better spent there.