Personally, I think it's a pretty awful idea. Most free games that use this system (there are some exceptions, such as TF2 and some others) are plain bad. Just horrible.
And then they have the *brilliant* idea of implementing micro transactions. What do you get? A s**t load of angry people because the players who pay get a 1-hit kill assault rifle.
And that really bothers me. It ruins all the fun of working hard for weapons, items and stats of both the buyers (they level up twice as fast, etc) and other players. (what's the point of leveling up if you know that if you don't play you'll never be able to beat premium guys?)
This is pretty much what I was talking about just above.
Most of the western games that have tried the "micro transaction system" does end up giving 1-hit kill assault rifles, when instead they should be giving things like in-game currency, or stat points that can normally be earned by playing the game... The end effect is essentially "saving time"... REAL time, in real life! Pay money = save time (casual gamer can keep up with the ******** hobo's with no life). The ******** players that don't want to spend the money get to the same end result, but can spend money if they want to save the "grind".
THAT is the "smarter" way to do it...
~Sol