I don't think any handheld strategy game can actually get as good as this.
Advance Wars: Dual Strike picks up right after the events of AW2, after the almighty leader of the Black Hole Army, Sturm, has finally been put to rest for the disaster he has done. But for some mysterious reason, The Black Hole Army in Omega Land has grown to enormous porpotions and started draining the land of its life power, leaving most of the land into lifeless heap of wasteland. To counter this, The Allied Nations (somewhat a spoof of the modern United Nations) has formed an emergency force with limited manpower and supplies and are fighting back to reveal Black Hole's true intentions.
AW:DS has some major changes in it, and most of them made this game 10 times better than the original. New game modes like combat and survival gives extra fun after you complete the campaign and war room. New features are new terrain, new Black Hole weaponry, and the almighty Tag Powers that allow for 2 attacks per turn and can guarantee an instant win if used properly. New commanders arrive from every faction to either preserve peace or to corrupt the land.
But the best feature of this game are the new units. Black Hole has advanced their technologies even further now- they now have three new units at their disposal: a vague-looking hovercraft named the "black boat" that acts like a repairing APC, a guided flying missile known as the Black Bomb which somewhat acts like a remote-controlled missile silo and a Piperunner, which, as its name implies, can only travel on pipes and is a hybrid of a MRLS (Rocket Launcher) and the mobile anti-air missile platform. The Allied Nations also has developed new technologies (but Black Hole reverse engineers them later anyways,) like the Stealth Fighter, which is a weaker fighter but it can fire on all units and can avoid being attacked by cloaking itself. Another new unit is the Aircraft Carrier, which can hold 2 planes and can resupply onboard planes. It can also rip other planes out of the sky with missile salvos. But the all-time award goes to Green Earth's mighty Megatank, which can destroy anything on land (with the exception of other Megatanks) with one volley of mega shells. But with every strong unit comes weaknesses. This unit lacks speed, fuel and vision range. It also costs a whopping 28000 credits so take that into consideration before making the purchase. Black Hole has also developed another mysterious weapon of their own, but I'm not going to spoil it. Hint: Not even the Megatank can defeat this monstrosity alone. Also one hit kills any unit if it gets too close.
Playing this game doesn't require the reflexes of a 10 year old on crack, all you need is brains, firepower, patience and a few tricks up your sleeve. A veteran should be able to breeze through the early missions easily, while a newcomer should take their time to listen to the tutorials. But don't worry too much, the game won't get TOO difficult to handle, so don't worry too much about 20+ Megatanks charging at you since there's no mission like that. But beware, the later missions sometimes do require a lot of smart moves in order to be successful.
So, after my extremely long review, my message is this: GET THIS GAME!!! No DS owner should miss out on this excellent game. It's nearly impossible to find nowadays, even in used bins, though.