The DS, should I get one?

[omoneru]

I was a hardcore gamer (and still am) and my gf was a non-gamer.  Initially I thought games on DS won't interest me because they looked "not deep enough", and then out of the blue my gf bought one on a whim.  You know what happened?  Not only she became a gamer, but also I've got one myself as well and we ended up playing on DS together.  I'm really happy that I made that decision. 

Part of the reason why it succeeded was that some of the 1st and 3rd party titles were surprisingly well crafted, and also that the incorporation of stylus and touchscreen made gameplay very intuitive and immersive.  Like others already listed on this thread, I would recommend titles such as:

Elite Beat Agents: Initially I thought I would never like this type of game, but it turned out to be one of the best games I've ever played.  Check out customer's feedback on amazon.com.  In addition, IGN lists this as the best DS title.  http://ds.ign.com/index/reviews.html?constraint.floor.article.overall_rating=9&constraint.return_all=is_true&sort.attribute=article.overall_rating&sort.order=desc

New Super Mario Bros: It's not just a remake. A lot of new ideas and challenges. Very fun.
Mario Kart DS: Fairly addictive racing game. You can compete with people around the world with wi-fi.
Metroid Prime Hunters: Online battle keeps its replayability quite high.
Tetris DS: Not just an ordinary tetris.  A lot of new modes and excellent twists. Online ranking system.
Advance Wars Dual Strike: Great strategy game, but you can't really find one on the market unless you pay extra.
Animal Crossing: Wild World: I play this with my gf when I want to relax.  It's slow and not very dramatic.  There's no enemy whatsoever. You don't have clear objective. Yet uniquely satisfying and relaxing. 
Hotel Dusk and Phoenix Wright series: Good adventure/detective games. Both have received raving reviews.
RPG: The Big Three - New Final Fantasy, Zelda, and Dragon Quest are coming to DS. 

You can check games in here as well: http://gamerankings.com/itemrankings/simpleratings.asp
Select DS as platform, make "Minimum Reviews / Votes" 10, and "Limit Results to" 50 and search.

Another thing,  the Japanese market has been dominated by DS and new games are coming out there left and right like you won't believe.  It's friggin crazy.  I know good titles have been and will be released for DS in Japan and they will come to the US eventually.  Because of this trend, it is only going to get easier to find good titles in the US.  DS is definitely a good investment as a gamer.

If you decide to get one, be sure to get DSLite (smaller, lighter, brighter screen - better in every sense). Never the older version of DS.