good
Good concept, and good implementation, but the time limit is gay. 30 seconds (or any other quantity of time) will not suffice in allowing me to memorize an entire intricate picture. By the same token, 30 seconds is no where near enough for me to look for differences (which takes far longer).
It would be better to have the pictures side by side. My memory happens to fail after about 10-30 seconds, so the game is about impossible (even the 1st level). I know I'm lame, but I'm sure other ppl will have similar problems. Even if they are side by side, it may take minutes or even hours to determine small differences.