I haven't done any sous-vide coking myself, but I am familiar with it. Think of it as a slow-cooker (with a dildo) but with PRECISE control over the cooking temperature; something that most slow-cookers are notoriously bad at.
By the way, if you want a slow cooker with much better temperature control than that thing on your kitchen counter, use you OVEN at the lower setting you usually ignore! Ovens are generally pretty good at temperature control!
The big beauty is - as Simon said, that with sous-vide you CANNOT overcook your food (if you set the temperature properly). NOTE: Fahrenheit and Celsius temperatures are NOT the same! For example, 100°F is body temperature, and 100° C is boiling water. But you knew that.
Digressing... I have a GE induction stove, and after it was delivered (!) I learned that the next model up from mine has a thermal probe for the induction cooktop, which essentially turns the cooktop into an induction sous-vide! Grrr! If I had known, I would have ordered THAT instead of the one I bought... Grrr!
OK, back to sous-vide... Try sous-vide with game meats - venison, goat, mutton, moose & squirrel ("Hey Rocky! Watch me pull a rabbit out of my hat!"). Try it with brisket or corned beef, chuck stew beef, or make a batch of Chinese Red-Cooked Beef Shank if you are willing to boldly go...
I have heard that sous-vide eggs are out-of-this-world.