I'll go with announced titles only, as otherwise there would be Zelda, Pikmin and such only.
1. Super Smash Brothers Brawl
(Massive distance)
2. Fire Emblem DS
3. Advance Wars Dark Conflict (didn't ship to Norway, so I'm getting it when I'm on holiday)
4. Starcraft II
5. Tales of Symphonia: Dawn of The New World
http://www.vgchartz.com/games/userreviewdisp.php?id=261
That is VGChartz LONGEST review. And it's NOT Cute Kitten DS