Most of us have totally forgotten this by now, but the first few months of the DS' life in America were a bit wanting. Sure, Mario64 was a cute port, but we've all played that game anyway. There were a few interesting concept titles like Yoshi's Touch and Go, and everyone (including myself, darnit) were totally missing the boat on Phoenix Wright.
Advance Wars: Dual Strike, however, was the first indication that the DS was headed for greatness. Anything Intelligent Systems does is usually gold, and of course these games were already heralded from being standouts on the GBA platform.
(A note: EGM's editor gave the first game a mere 7.5. The media totally missed the boat on Advance Wars I, simply because it didn't sport a polygon and didn't use a hip gameplay style. Of course, as Dave astutely points out, they then overreacted with Advance Wars 2 to a ridiculous degree.)
Advance Wars features turn based, tactical gameplay. Think X-Com, UFO Defense, Fire Emblem, Final Fantasy Tactics etc. You take command of an army, led by a Commanding Officer or C.O. (in usual Japanese weirdo style, the armies are headed by 16 year old kids, a really fat bald dude, a WWI era German dude, and a Dukes of Hazzard style hillbilly). You build units from factories, using money that you earn from cities that you "occupy," thus neatly borrowing some elements from real time strategy games. The units have pretty obvious abilities. Jeeps are good for scouting but stink when pitted against tanks. You have regular soldiers who are, well, cannon fodder, and "techs" who carry rocket launchers (and can actually do decent damage against bigger vehicles).
If you've played any RTS games lately, you know how hard it is to make out what a unit "does well." For example, in EA's "Lord of the Rings: The Battle for Middle Earth II," how are we to know if the Ithilien Rangers are better against Spiders or cave trolls?!? The simplicity in Advance Wars "Paper Rock Scissors" combat allows you to get in the game quickly, yet this is certainly not a simpleton's game.
Also rounding out the gameplay experience is C.O. "powers." You officers have special abilities that are available when their power meters fill up. This is good, since you'll be depending on them often to bail you out of tough spots. The evil C.O.'s you face in battle, however, have these as well.
The graphics are typical 2D, glorious to behold in our polygon obsessed age. Characters, tanks and scenery are drawn in an obvious, J-Toon style.
Sound is a strong point in this game. Every C.O. has their own theme tune, and some of the are extremely well composed. The DS's internal sound bank is put to great use here. There are many pop genres represented, from funky rock, alt rock, metal, hillbilly (with hilarious sounding banjo riffs) and dance music. Fortunately, you can unlock a jukebox feature later. This is one game you might consider dumping the music into your computer to put on a CD.
Story and narrative are pleasing but not great. This isn't Fire Emblem; the Advance War characters are cartoonish, and the whole thing has the feel of a Saturday Morning cartoon. There are some nice moments, but you'll just be wanting to get to the next battle.
I'm not sure I have many complaints here. I'll admit, I love all things turn based, so for me, there isn't much not to love. Some folks will be a little turned off by the presentation, but that is inconsequential to the gameplay. There are some interesting mini-games presented as well, including "Combat," a semi-interesting real time game. One complaint: I wish they had implemented Internet play for this one. It would be sweet to take on players all over the world.