I've been looking for a reasonably-sized, non-stick double boiler for quite a time as the non-stick lining of my old one, bought years ago, is wearing out. I make real porridge at least once a week: pin-head oatmeal poured into hot milk, stirred with a spurtle and gently heated in a double boiler for about 15 mins in the evening, salt added and then left overnight to soak and swell off the heat. In the morning it has thickened and just needs to be re-heated in a double-boiler. Take it from me without a non-stick lining a lot of soaking and scrubbing is needed as oatmeal, especially cooked in milk, sticks like anything! This Clearview Porringer is even better than my old one in that the inner pan has a round base which makes it easier to stir the porridge and also to clean as there isn't a right-angle between the base and sides of the inner pan. A fault in some double-boilers is that the gap between the inner and outer pans has too tight a fit and when the water in the outer pan boils it creates a pressure build-up and hot water spurts out carried on steam. This porringer doesn't do this. The build quality is good and nicely heavy. The glass lid also fits into the outer pan which makes it a useful little sauce-pan for use at other times.
I can see that this double boiler will also be excellent for making egg-based custards, keeping delicate sauces warm or melting chocolate.
Update October 2010: The porringer's non-stick surface is still in perfect condition after being used at least once a week and my porridge stirred with a wooden spurtle. It's washed in a dishwasher which has'nt affected the surface. if, like me, you sometimes put too much water in the lower pan you can stop the water bubbling up by putting a cork between the two handles held in place by an elastic band. Too much water is better than too little. I've occasionally left the porringer on too high a flame and the water has boiled dry so I routinely use the cork ensemble to be on the safe side.