Play money serves no purpose for learning except to learn the basics of the game. Real poker strategy does not exist at the play money tables because there is nothing at stake. Even some freerolls are a joke. Have you ever played in one of the Full Tilt Poker After Dark freeroll donkaments? Half the table is all-in on the first hand. I have won a couple of these freerolls - know how? All-in first hand, win it and then can push the table around with my huge stack.
I feel to get a true "feel" for online poker you have to play for real money.