Rather than buying one of those rather unsatisfying cappuccino pod machines, where the result never really tastes like cappuccino, or going the whole-hog for a Gaggia, this frothing jug can quickly make several mugs worth of really frothy milk in less than a minute. You can do it with hot milk or cold milk, depending on what you want to get, although, because this is a metal jug, you can't put this one in the microwave. One of my colleagues, who used to be a barista in a coffee-shop, felt the texture was excellent, but the milk really ought to be hot rather than cold for the authentic effect.
If you're in the dark about what this does, essentially it twirls around a couple of rotating nets in the milk, a bit like using a whisk, but much, much quicker because the pump action of the thing on top is geared to make it twist very, very fast. You could do something similar with an electric mixer, but it would take longer, and it wouldn't be as good, because the netting has a very fine mesh.
You _can_ put it in the dish-washer, but it might not do you much good -- we found that the dishwasher really didn't clean the milk from the the twirling filter, which means that you have to wash it by hand, or suffer milk which begins to taste like yoghurt. On the other hand, it's non-stick, and so a fairly easy hand-wash.
This is a great device, but not perfect. The exterior scratches easily, and it needs about 1/4 of the jug to be filled with milk to froth at all. The bottom centimetre doesn't really froth at all, which means you will waste a bit of milk each time if you aren't doing a lot of drinks.
Good though, nonetheless.