Use Ours Quite Often
Thing to remember is that cooking pressure is simply a high tech way of using moist heat to prepare food. Thus any dish that one would normally simmer, boil, steam, poach, etc... in theory should come out the same if not better.
OTHO things that require dry heat such as roasts and certain fried foods are best done the normal way. Pot roast for instance will come out well in a PC, while roast beef usually results in a grey hard looking brick of a thing.
As with microwaves there are tricks and methods to get around certain failings of using a PC for things that are normally dry cooked, such as pre-browning meats (searing) and so forth, but there again still results may vary.
Finally consider certain types of pressure cookers require more water/fluid than others to operate properly (build up enough steam pressure). Older and some modern units from Presto and others require more whilst Magefesa and such use less. Using less water means less dilution of vitamins and such.
