People who say the DS even outperforms the GBA have descended into a level of fanboyism that is impossible to escape from. That's the problem with most Nintendo fans these days; they've created their own little bubble where gaming reality doesn't exist and you think something is good because Nintendo says it's good.
GBA has two-thirds of the buttons, half the screens, and a purpose. No system can be worth the time unless the company making it is confident enough to sell it without constantly reminding you that it's the best thing ever, as if you'll suddenly think for yourself without them continually whispering in your ear. DS suddenly appeared on the scene, there weren't whispers about it months and years beforehand like there are with other systems, only after the PSP was announced did Nintendo say "Hey! Hey! Look at us, we're making something TOO! Now give us a couple of months and we'll tell you what it is and how it works~"
Gameboy has survived on reputation of unbeatable gameplay and amazing simplicity longer than most people at PC have been alive. It arose out of necessity in the game market for something that surpassed Game & Watch and other early one-game handhelds and has survived the transition from original to pocket to color to advance to SP, only increasing in quality each time. It was the thing that other companies targeted and failed to bring down, not the other way around like Nintendo is doing now. It didn't exist to spite a successful competetor, and each change was made with the player in the mind, not the pride of the company. I don't want to own something that is only making me a tool in a duel of honor.
Portability =/= superiority over consoles. You also can't play Gamecube games on your DS. It works both ways. Games are made for a certain system because they're considered most suitable for that system. You have to sit down to play a DS, it's not like you'll be running and jumping with the characters o_O (unlike the Revolution...*coughfullbodydscough* -_-) GBA is portable too. So are a lot of other systems. But if you don't like consoles for being consoles anymore, so be it *shrug*