Good
The animation is good. The characters and a few objects appear to be hand drawn which is a nice effect that causes them to stand out from the background. The animation is smooth and what hasn't been drawn by hand has been animated fairly well in flash. The only problem is that they appear a bit pixelated. It's better to draw them large and scale them down accordingly than try to draw them small and scale them up, as quality is lost in the process. The happy, cartoon style in the scene where the two brains are together is a nice touch that shows the happiness within their minds which is then shattered by Dr. Cerebrum.
The audio is good. The mood of the music changed with the mood of each scene well. The music is good. You can tell the audio was designed for the animation.
The plot is great. It's sad, it's happy, it's sad, and then it's happy again when you don't expect it to be. This isn't a simple, easy to guess plot. There aren't many moments where you can tell what is going to happen next. There is enough suspense to keep the viewer interested and actively engaged in the story. The plot is certainly the best part of this flash.