I do leave mine on when I go out. I used to worry about it boiling dry, but that doesn't happen so much compared to a saucepan simmering on a hob.
I will do a whole chicken in mine, but I put it on a raised plinth because I find they exude so much liquid that it will be boiled rather than roasted if I don't. You can make the plinth out of vegetables, but I find vegetables don't cook well on low. (Stews are OK on high, but frankly not really better than with a saucepan on the hob.) The chicken tends to collapse into a pile of meat and bone when I take it out, but that doesn't bother me. (Makes it easier to strip the meat when I make the left-overs into a curry.)
Re-heating cooked food in the pot in a microwave doesn't work well for me because it takes the pot too long to warm up, and the pot cools the food. I need to take a serving out and put it on a plate and microwave that. (Which is arguably more hygienic than repeated reheating food anyway, although that doesn't bother me much.)
