After seeing the Corocoro scans, the main things that intrigue me are the battle system and the more 3D aspect of things. I'm mostly interested in the battle system because it seems to be a more frontal view with the entire Pokemon shown in the back-sprite, not just an upper body shot. Plus it seems to have 3D animations in the attack that the single screen shot shows.
As for the more 3D aspect of things, I really hope that city that there's a picture of is either a beta picture or there's more buildings you can actually enter when you go further into the city. I'd hate if you could only go into, say, the Pokemon Center, Mart, and Gym only.
There also seems to be something hinting towards a vehicle, which makes me think of Pokemon Colosseum. I really hope it's something to make travel easier or only used at certain parts, I hated not being able to explore the wilderness and run into wild Pokemon in Colosseum. Of course, I guess we'll find out whenever they reveal more things.
Also I wouldn't say that It's for the DS just yet... even though we have a few screen shots it doesn't mean it's on the DS for sure. There's still a chance it could be for the 3DS. although it seems like a slim chance.
Actually, it's been confirmed for the DS ever since the main site updated that they had a game planned, before they had their names.
As proof:
http://www.pokemon.co.jp/info/2010/01/g100129_02.html
That link will take you to the info page about it, and you can see "DS" near the bottom.
EDIT: Thinking about it, the main Black and White teaser site has the DS logo at the bottom right and says it's for the DS in the little info bar. I should really check these things before using older sources.
Adding the link for the sake of convenience:
http://www.pokemon.co.jp/bw/index.html