I bought a new 3000 and 2000 and tried a bunch of games on both side-by-side.
PSP3000:
It had noticeable interlacing in most situations.
The colors were more saturated, but dark colors were too dark, and whites seemed tinted.
I tried 2 different 3000s and both had backlight bleeding and some spots on the screen were lighter than others.
PSP2000:
No interlacing effects, but there is noticeable ghosting in very fast movement, especially when it was something black moving.
The backlight was perfect and even.
Picture is bright, and whites look white.
Comparing the picture between the two, it's kinda like the 3000 had its brightness turned down, and the color turned up, in TV terms.
When I turned OFF the enhanced color on the 3000 and put them next to each other, the 2000 looked better.
It was a hard choice, but I ended up keeping the PSP 2000.
They both look good, but have small issues, so really it comes down to personal preference.