Had one for many years now but the jury is still out i'm afraid.
i find that any joint of meat...eg chicken, beef, lamb etc just literally falls apart when you've slow cooked it. Yes it's deliciously tender but you can't carve it and i've found beef just comes out like corned beef !!!
As a result, i much prefer to oven roast joints as you get the nice skin, caramilised bits and crackling on pork !!!
However, for some of the tougher cuts such as mutton, it's ideal. I've also done stews and caseroles in there and they've been devine. You could probably do mutton curry in there....i'd imagine that would be awesome.
For winter stews, i just use any kind of meat...beef is good though, and add loads of vegetables of your choice...chunky carrots, turnips, onions, mushrooms, peas, sweede....the choice is yours and then i just add some gravy or stock. Season, add some herbs such as rosemary or thyme and it'll taste awesome.