In theory, a demo is a very effective advertisement.  Your market actually wants to be sold on the game, and you can choose whatever best highlights the final product.

However, a certain degree of honesty is inherent in a demo, something which is entirely absent from pre-launch hype.

With the advent of systems like the PSN and XBL, console gamers have had the opportunity to try before buying.  While some people have certainly been convinced to buy a game they'd never heard of, how many people have been convinced to pass on a game that they were excited about.

Some recent PS3 games come to mind - among message board communities, it seems that the Heavenly Sword demo actually reduced anticipation for the final game, and one wonders whether or not Factor 5/Sony is sending entirely the wrong message by refusing to release a Lair demo.  Even the Halo 3 beta seemed to elicit more criticism than enthusiasm.

Wouldn't it be a better idea to make like PC developers, who, if I remember from my days as a PC gamer, tend to release demos well after the commercial release of their products?

Doing so would allow developers to cash in on those who are convinced by pre-launch hype while still reaching people who would otherwise have been ignorant or on the fence about the game.

I agree there are dangers, but I suspect that game developers will begin to hone the art of demo-making. Which is to say, as time goes on, they will become better and better at using the demo as an advertisement, and will expertly avoid "demoing" any portions of their game that might still be rough or is generally less exciting.

Think of movie trailers, as a possible parallel. Even in my life time, I've seen movie trailers evolve, as film distributors learned how best to use those thirty seconds to make their movie appeal to the consumer. There's always, always the danger that you will turn someone off of your product -- I agree with you on that -- but I think that danger will lessen with time and experience.  

It didnt, most people whining about it did not even play it. All the previews based of the demo have been quite good.  Mistake with halo was that it was to early for that big a beta.

Yeah, I agree. A well polished demo can do a lot. I really considered buying The Darkness today after playing the demo. Then I remembered Warhawk, Lair, and Heavenly Sword are all coming out very soon, and that I still have a huge backlog of games (including Oblivion...).

In any case, a good demo is a good investment. You can just use levels from the game too if cost is an issue. They used level 3 and 7 from the game in The Darkness demo.

The Heavenly Sword demo was kind of sloppy since it was so short, but it still made me want the game more. The combat system was pretty enticing.

The problem with Halo was that most people don't seem to understand the difference between a beta and a demo. The problem wasn't with teh beta itself but with the people who misunderstood its purpose

Demo making is a new(er) market for consoles, in the way of that they are readily now available.

However, demos for games have been around since the PS1 era for consoles - I remember playing tons of great demos (like twisted metal) back in the day and loving it.

It'll take time for developers to make great demos all the time - nevertheless, thus far, the demos have helped prevent alot of gamers from making real bad mistakes (Hour of Victory).

However, there are games like Blue Dragon that have so-so demos (in some people's opinions) that are/should be awesome games.

Either way, I think that creating a real strong demo will be a huge key for non-AAAAA games to do real real well. Oblivion, Gears of War, Call of Duty 2, and a few others never needed demos to do real well. But for lesser known, but great games, they have a chance to do real strongly. Ace Combat 6 is a great example: the demo was well recieved (as far as I know), and managed 500,000 downloads it's first week. For a game like AC6, to a new console, this is real good.