Also, you can't play mage as you play melee character. And even in low levels they can be "monsters" in killing most enemies with one hit. Of course, you need to use magic to achieve this (I start with fireball).
Later people say they get much stronger, but from my perspective, mage with Grissenda is pretty formidable from start. You can get Grissenda with L2-3, so, from very start mage is strong.
It doesn't mean you won't die at all, of course.