It's actually a pretty good game, especially given the hardware it has to work with. And comparing it to the original 2D GTA is a complete oversimplification. I played the original GTA, guys- this was a game where getting shot once killed you and little bounus points sparkled up on the screen when you ran over pedestrians. You can kind of see where GTA 3 came from in it, but as a game the original GTA is an innovative and fascinating trainwreck. By contrast, Chinatown Wars is a game where you could almost believe it would be a 3D game if you could unlock some cheat code to get the camera to rotate downward. It has a fair amount of depth and variety in things to do and ways to do them, and the visual look of the streets and cars, while not blow-you-out-of-the-water, is really quite good for the DS's capabilities and certainly better than functional.
If there were two major criticisms I'd make, it's the driving controls (one pixel is the difference between a huge accident and scraping by without loss of momentum- not the best fit for the directional pad) and the plot. I have the same problem with a lot of the GTA games, really; I keep asking silly questions like "Why is my character *doing* this, especially for *this* person?" In Chinatown Wars, the protaganist would quite literally save himself a world of grief and shorten the game by a few hours if he started shooting people in the face the second or third time they insult him and threaten to kill him, rather than accepting their missions despite the ill-treatment. Seriously, Huang- grow a pair!
Now, I have a perfectly legitimate copy of the game. I don't really know how prominent piracy is on the DS (and I'm happy to hear any hard statistics anyone might have, but I'm not really interested in anyone's say-so), but I find it hard to believe that OF the portion of the DS's sales that is teens to adults, and OF the portion of that who are interested in GTA, that the majority of those are hardcore pirates. But there is a problem with any console game with a "long tail", especially one that doesn't necessarily have a lot of replay value (and honestly, the non-plotted side-quests in CW didn't really do that much for me) is that it's easy to get the game used, like I did. And used copies don't really show up on sales charts.
So, yes, it's a top-down GTA game, one with slightly cartoonish cel-shaded graphics, and that may have turned some people off despite the good reviews. And it's a mature game on a system that does a lot of business with the teen-to-tween crowd, whose parents by now have probably finally gotten it through their heads that a GTA's "M" rating is something they should take seriously. And frankly, even in the few ads I did see, it's hard to get across just what playing the thing is like; how much of the GTA "experience" it manages to squeeze in. Instead we get stereotypical asian music and cartoonish pictures of the characters, not exactly something to sell the thing to anyone. It's also a game that frequently sells for upwards of thirty bucks on a system with many good titles available for much less.
All I can finally say is that it's a shame if it's mediocre sales causes other manufacturers to shy away from games on the system geared towards adults that feature some depth and complexity.