They take a long time to die from sunlight. This can be a problem for new games starting or having died and trying to get your body again. This afternoon it happened to me that there were 3 zombies, 4 creepers and a spider all trying to kill me as the sun was coming up. Needless to say I died a number of times because of those darned Creepers! Without a weapon or armor, it is hard to kill the mobs and waiting for sunlight to kill them take to long. I am suggesting that it take half the time for sunlight to kill a mob. In fairy tales the ogres turned to stone instantly when exposed to sunlight; that is to fast I think. Taking half the time is a good compromise.