Advance Wars comes to the DS with twice the charm. And twice the mayhem.
There's nothing in this version that couldn't be incorporated into the GBA. It's even to your advantage to use the D-pad instead of the stylus since it's very easy to peck out the wrong command which get very tidious in the heat of battle.
Another new addition is the inclusion of two commanding officers. You can switch them in between turns to access different special abilities. It gives you more flexibility and is more reactive than proactive since you'll probably use it to counter one of your opponent's brilliant moves. You may have heard about the inclusion of a real-time battle mode and while it does exist, it's not nearly as much fun as you might be led to believe. It's slow and cumbersome. The controls are sluggish and the distances are too far apart to generate any sense of immediacy. It's a novelty that you won't get much replay value from.
With some graphical upgrades and the above-mentioned additions, Advance Wars: Dual Strike is recommended for those that already have the DS and want to experience a game that tests their gray matter instead of their trigger fingers. If you're a fan of the GBA series and you're looking for something new and different - keep looking - and let me know when you find it.
Overall if you care to take Avanced wars to two screens then yes it is worth it. the overall presentation of the game is at a very high quality, the AI is as easy or as challenging as you want. It'll take new-comers a few hours to work this out however once mastered you'll be able to enjoy possibly the best action turn based stratagy game on the DS so far.