Aside from its good graphics, the DS version of Tomb Raider Underworld doesn't really succeed in any department.
One feat that I would commend the developers for is that the FMV cutscenes are all here, and all are intact, without any loss in quality. That is something that induces a 'wow', but let's get onto the actual game. The story is the same as the console version - in other words, it's very good, but after that it's downhill.
The graphics, like I said before, are amazing for a DS game. There is no slowdown like in other 3D games on the Nintendo DS, and the lighting is great. The character models aren't HD, of course, but they look very good on the DS.
The gameplay is on the easy side. Like, disappointingly easy. Sometimes you die because you don't expect it to be so easy and overshoot. Unbelievable. And there is no increase in difficulty as the game goes along.
The game plays like a 2D side scrolling platformer, but with 3D character models and environments. You use the touchscreen for the inventory. And man, the screen is dark! You'll only be able to see everything if you play on a DS Lite on the highest brightness setting. It's easy, even though Lara has all her moves from the console games like hanging from ledges, swinging around poles and using her grapple, because it's side scrolling. You can't fall off because you jumped a little too much to one side.
It should take an average of less than six hours to beat this game. So what good you can take from this game, can be taken from its screenshots - the graphics. Aside from that, unless it's your life's goal to collect every Tomb Raider game on every platform, or you don't have any other console to play this on except the DS, I would dissuade you from playing it.