Ginnipe said:
But if you use linearity then a game generaly has a much better story and the expeince will trump open worlds'. Take Half-Life 2 and the original Halo, they were great games with scripted events that while happened no matter what, still imersed me much more than a GTA or Mercinaries. My point is is that linearity makes a game feel more imersive and in my eyes is much better than and open world game.
It totally depends on the type of game. Don't worry, linearity isn't under threat; open-world games aren't nearly as new as people make out. They were around long before Grand Theft Auto. Mario 64 has a lot of open-world elements; so does A Link To The Past. In all that time they haven't affected the popularity of linear games, and they're not about to start now, they just seem to be increasing in popularity because the term "open world" is being used more often about more games.
Here's a rule of thumb: linearity suits tightly-crafted narratives; open worlds suit player experimentation. If a game is primarily about the story, it should be more linear; if a game is primarily about the player's abilities and the game world, it should be more open. That's just a guideline, of course.
Have a look at this article about game design styles [http://lostgarden.com/2009/03/what-is-your-game-design-style.html]. A developer who focuses on Experience and Narrative will find it easiest to make a good linear game, but a designer who focuses on World, Player Skill and possibly Systems will get more out of making an open world game.