Blizzard is now offering a free Starter Edition of Diablo III. With this new edition, you can play through the game up to the Skeleton King boss (in Act I) and level your character up to 13 completely free of charge. Obviously, this isn't a well-rounded view of what each character can do, but if you play with each class, it should offer you some insight as to the variety of play styles.
To get the free Starter Edition, you can use any of the following steps taken from the official Blizzard statement:
– Log in to your existing Battle.net account at http://www.battle.net, and sign up for the Diablo III Starter Edition through the "Your Game Accounts" section.
– Create a new Battle.net account here, and the Diablo III Starter Edition license will be added to your account automatically.
– Grab the Diablo III game disc from a friend, install the game, and then log in with your Battle.net account. The Diablo III Starter Edition will be added to your account automatically.
If you play through the free version and decide you'd like to own the full game, all of your progress and achievements will carry over to your upgraded full version.
It's about 1-2 hours of entertainment for free and if you play all of the classes, that's longer than most retail titles lately, so give it a shot. The only thing you have to lose is your free time.