Diablo 3 is absolutely amazing! Once you beat the main campaign and go to adventure mode, it gets a bit repetitive, but the things you repeat are so fun it doesn't even matter. And class wise, I can give you some descriptions. The wizard does plenty of damage, but is the quickest to die. So if you can stay out of everyone's way, Wizard is good. Demon hunter is almost balanced with damage/defense but you probably want to stay back with him too. Barbarian's are melee characters that do tons of damage and have decent health. Crusaders do tons of damage and their health regeneration is so good (If you put your skills on regen) you'll eventually be generating more health than you're losing. I've never played as monk or witch doctor, though.