I was a bit worried that this mystery product would be a massive let down, nothing as substantial as a new kind of portable. So I've been very pleasently suprised here.
At first, when I read about it, I also thought "the dual screen thing sounds a bit silly". But then I decided to actually think about instead of just bashing it. Here's one idea for an application of this handheld:
One of the fundemental problems in computer Football games today is that you can only see a portion of the pitch. A player, in real life, can look right out over the field of play. He can stand at one end of the pitch and see someone 60-70 yards away starting to make a run, and so attempt to hit a long ball to him. The problem is in a computer game you need to be reasonably close to the player your controlling in order to be able to keep the ball. You need to be able to see were the ball is at a players feet and exactly what is happening directly around him in detail. Because of this you can never see anywhere near the whole pitch without compromising the gameplay. Games have attemped very small maps of the entire pitch at the bottom of the screen, with little dots moving around to represent the players movement on the pitch. But those maps are pretty useless. For a start they're always to small to accurately show you what's happening on the whole of the pitch. Also they're overlayed over the main view so they're hard to see (with the pitch and players running behind the map.. its confusing).
But with DS one screen can be for the main game and the screen above can be used as an interactive map. The interactive map would have several functions. The two main functions I would like to see would be attacking half and defensive half views. Say you have the ball in your own half, you switch the map (maybe with buttons on the back of the handheld) to the atacking half of the pitch and you can then see, in decent detial, what all the players ahead of you are doing while also being able to see what your doing. You can see a player making a run and pass to them even if they're 50-70 yards ahead of you. Or if you lose the ball in the opposing teams half, or in midfield, you could switch to defensive half to see where your defenders are before deciding what action to take. For instance you might see that your defence is organised poorly at that time, their may be a big whole right through it. In which case instead of putting your efforts into winning the ball back, you might put your efforts into first filling that gap and organising the defence. All the while, when your moving a player back to help strengthen the defence, or whatever, you could be keeping an eye on the opposing player with the ball on the other screen to make sure he doesn't become a problem for you. When the defence looks good you can then go and try to win the ball back, or if you see that it becomes urgent to win the ball back straight away you could do that instead at any time. I'm sure this won't interest some people, even some Football fans won't want to get that strategic and complicated. But for the real Football fanatics, of which there are LOTS, this would be fantastic if done properly.
Another interesting view in the interactive map could be a closeup of the apposing penalty area. You might be looking for a good pass, but you can also be keeping a very detailed eye on the keeper. If he strays off his line, or is just not in a great positio, you can see it and perhaps try to chip him.. This has SO many posibilities for taking this particular genre of game to the next level!