No one was expecting the current 900-pound-gorilla of the MMO market to throw its hat in the ring regarding microtransactions, but the fact that it's in the mix has forced a large number of people to take a look at the philosophies and patterns of the business model. Killed in a Smiling Accident recently put down some thoughts regarding the differences, explaining that World of Warcraft's model is, in their opinion, inferior to the one found in the equally-significant microtransaction model of Dungeons and Dragons Online. The former has a store consisting of fluff items with no equivalent in the game, while the latter largely puts forth offerings that can be obtained in the normal game if you want to take the time.
Of course, there's the obvious counter brought up in the comments: that it's better to have microtransactions selling something you can't otherwise get in the game. Simply take a look at Champions Online and the controversy over retcon pricing to see how the two can be better left untethered. Getting something unique is a nice bonus for a game you enjoy -- for example, look at the bonus costume packs that City of Heroes sells. However, with items on sale that can be obtained from gameplay, the game can feel a bit more disjointed. There's a case to be made for both sides, and with the free-to-play model gaining speed, it should be interesting to note where the majority of MMO players draw the line.
