Pros: Wow. And did I mention, wow?
Cons: Takes time; need some arm strength to empty the thing
My husband and I looove to cook. So I got him a copy of the book set "Modernist Cuisine at Home" for the holidays, and he got me a few of the gadgets that go with it, like the SousVide Supreme Water Oven. I know, it seems like overkill---it seems like an expensive one-use item that'll just take up needed counterspace. And yet, it's totally worth it if you love to cook.
First of all, if you don't know whether it would be worth it for you, then I encourage you to try one of the water bath recipes that doesn't require an appliance (there are a few that go for a short enough period of time at a low enough temperature that you can do them with stuff you probably already have at home)---if you do a Google search for "sous vide salmon modernist cuisine" one of the top links should be titled "Cooking Sous Vide---In the Kitchen Sink". Try it. If you don't think the resulting salmon is THAT MUCH better than other preparations, then the SousVide Supreme probably won't be worth it for you. When we tried it, we made one salmon fillet with the water bath/finish on the stove method, and made one using another standard cooking method. The difference was far greater than I'd imagined. The salmon was the perfect just-done temperature throughout; there was no dryness whatsoever; the flavor was divine; the texture was buttery-flaky; and the step of finishing it off in a pan of butter and seasonings gave it just the right touch of flavor and surface texture.
First, you fill the sous vide bath with water such that it won't fall below the minimum line nor go above the max line (there's a lot of leeway there, so it isn't tough to manage). You program the desired temperature and let it heat up---this stage can take a half hour plus or minus, depending on the temperature. You put the food to be cooked in a ziploc bag (if the temperature is low enough and you're using good-quality bags), press out all the excess air, place in the rack in the water bath, cover, and allow to gently cook for anywhere from 20 minutes to several days, depending on the application. If the temperature is higher and you aren't working with liquids, a vacuum-sealer (such as the FoodSaver) is a handy tool to use in place of a zip-loc bag.
The lid of the sous vide supreme can double as a platter/staging area where you can open up the bags when done. It also has an insulating pad that can double as a trivet when the lid is hot. There are offset handles on the sides to enable you to more easily pour the water from one corner after it has cooled (note that this does take some arm strength). There is a built-in timer, and temperature can be read/programmed in either F or C. The temperature stays within 1 degree of the programmed temperature, and convection currents ensure that all of the water remains properly heated.
Okay, so it's awesome at producing tender salmon, perfect rare steak, and a delightful pork loin. Again, all because you cook it to the same perfect temperature throughout; you keep all the juices from evaporating (which also prevents volatile flavor compounds from evaporating); and you don't have to worry about overcooking as long as you're heating it at the target temperature. Still, that sounds like a kind of narrow-use item.
It shouldn't be too surprising that you can use it to cook tough cuts of meat for long periods of time (this is where that multi-day cooking time comes in), producing a surprisingly tender result.
You can also, however, use it to produce some other rather surprising items. For example, infused oils. Also, there's a recipe in the aforementioned "Modernist Cuisine at Home" cookbook/technique book that produces the most incredible soft "scrambled" eggs---first you cook them sous vide, then you puree them. If you have a whipping siphon, you can then further turn them into a sort of foam. There are also some other surprising recipes that use eggs or yolks that have been cooked sous vide, such as a fantastic pie/tart crust, and a delicious pastry cream. It's the perfect way to avoid curdled egg, since it never gets too hot.
Although we haven't tried it yet, you can also cook vegetables sous vide (that comes next!).
The oven is incredibly easy to use. It requires a little prep time for heating up, and it can take a while to cook depending on the application; this definitely isn't for people who just want to whip up a 10-minute dinner after work. It's for folks who really enjoy spending some time in the kitchen and who want to get every last bit of flavor and perfect texture out of their food. It makes an awesome gift for your favorite foodie!