i find that they are very useful on photoshop, but you need to experience using them a lot. they allow you to stack images on top of one another which can create good effects by using them in different ways.
Bet when I'll find out I'll be like "omg so that's why" just like when I learned how to use the pen tool lol.. but all I use layers for is doing lineart.. why are layers so important besides that? I really can't see <_<
