With all the buzz about BPA and dangerous chemicals leaching into food-- ESPECIALLY when the food is heated! I've sworn off any type of plastic "microwave safe" dish for a few years now.
I only use glass and sometimes a ceramic cup or plate.
Also you have to beware of any frozen foods that come all ready for heating in a plastic dish. To be safe, you must remove the food from the plastic dish and put it in a glass dish.
Do lots of other folks have similar concerns about microwave dishes? I've seen lots of buzz about BPA in cans, but very little about what to microwave safely in.