I read an article which is very amusing. So quoting from the Escapist, here are the details of his piece:

Each time a new game is announced, gamers react in the same manner:

1. There's a slight pause and an intake of breath as people read, sit back and digest what they have just seen.
2. The net becomes a flurry of activity with fiber optics burning brightly as people clamor to find out more.
3. Repeat No. 2 as necessary until the game is released.

With each blog post and forum thread, the gaming community's expectations rise. What cool features will it have? Will it look better than its competitor? Will it be enough to justify shelling out the cash?

But therein lies the problem. From a developer's point of view, the way gamers react to everything from the initial announcement to the release date can have an impact on the game itself.

Gamers are a shrewd bunch. Each time developers release a new piece of information regarding their work in progress, the gaming community snaps up every shred and meticulously pores over it. With each screenshot and list of potential features, their expectations for the game gradually coalesce into a snowball of hype. And while it can cause games to fly off the shelves on release day, hype can also be fatal.
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When developers release screenshots, they want make the game look nice, flashy and drool-worthy. And when they release information about a game's features, they often err on the side of excess. Inevitably, with each snippet of information released, the chorus gets a bit louder: "This game is going to rock." "Kick ass." "Looks awesome." "It can do what? Wow!" Sound familiar?

But what happens when, due to budget, time constraints, publisher demands or a whole host of other issues, they have to cut out some of those cool features down the line? What happens when they release screenshots that lack the polish of earlier images? Gamer expectations plummet, disappointment sinks in and hype quickly gives way to resentment. "Hmm, doesn't look as good." "Man, what a downgrade." "Last generation anybody?" The list goes on.

It's a delicate balance for developers and publishers to cultivate interest in a game while managing players' expectations. The question often is, how much information should they make public? Release too little and there's no buzz, no excitement, no word of mouth. Release too much information, and you run the risk of disappointing fans when the game is released. So which is best?

Read it more here:
The Escapist: Managing Expectations