Diablo III is doing partial free play wrong.

Diablo III has a Starter Edition (currently requires guest pass) that makes it possible to play a limited amount of the game for free: http://www.geek.com/articles/games/how-to-play-diablo-iii-for-free-20120515/

"As for what the Starter Edition includes: you get to play through Act I of the game up to the Skeleton King. You can’t take a character past Level 13, there’s no access to the Real Money Auction House, and matchmaking is limited to fellow Starter Edition players. Even so, this is just a (free) taster of the gameplay by the end of which you should know for sure if you want to buy the full version."

I call this doing it wrong. That's nothing more than a demo. Doing it right, is what Hellgate: Global does. They claim to be free-to-play, but that's only for the first half of the game. Halfway through, there's a paywall. However, it's possible to buy the needed pass with in game currency from other players. This is very similar to EVE Online's PLEX system, and makes it possible for people with more time than money to get access to the game for free, while also undermining the black-market gold sellers. It also can bring in lots of money.

D3 already has a real money auction house, so it seems silly to me to not allow free players to obtain real money in the auction house by selling goods, and then use that real money to buy the game. Locking them out of the real money auction house just makes it harder for fans to buy Diablo III.