Oh, for fucks sake. It will take years before a SOC (system-on-a-chip) GPU can push as many polygons around as the PS2 did. Their size, power and heat restrictions are gigantic barriers which make them evolve at much slower rates, performance-wise, than bigger GPUs.
And I'll bold it because seems people aren't fully aware of it: Sony "cheated" with the PSP and used a gigantic GPU that is almost as big as a laptop GPU. That's why it took fucking years until we started seeing comparable graphics on mobiles like the iPhone 3GS and now the 3DS.
We are comparing a 6-years old netbook-class GPU against a mobile-class GPU.
1) Geometry: it is too early to tell and the games shown are all over the place, but the 3DS seems equivalent to the PSP on this level. Both are below PS2.
2) Shaders: from the looks of it it's quite obvious the 3DS is using an OenGLES 2.0 GPU, which supports programmable shaders in enough capacity to do fully normal-mapped characters with specular lighting (MGS) and self-shadowing (SFIV, RE). This is quite a step forward from the PS2, the PSP and even the Wii (all per-pixel effects on the Wii were merely hacked environment maps).
3) Resolution: 400x240 is close, but below PSP's 480x272, but there is the 3D. Both are lower than the PS2/Wii 640x480
4) IQ: no dithering to be seen (a staple on the PSP and PS2 and on many Wii games). Some games seem to be using MSAA (it's necessary for DS backwards compatibility but it's hit on performance is unknown). AF support not confirmed.
I believe with the 3DS Nintendo finally has a handheld that is the "sweet spot" of graphics capabilities: good enough to allow a wide range of game types and graphical styles, but simple enough to make the developers life easy. That they can do it all while running in 3D is quite a feat, but the jury is still out until battery life and price are revealed.