I thought that there was a lot of room for improvement. The flash gave me a bad impression from the start and it did little to improve upon it as the flash played out. The graphics were good enough, but they weren't exactly great. The slightly sloppy style seems to be quite popular so I won't be complaining about that.
The major problem with this flash was the voice clip. The quality of the recording wasn't great and while I could make out what was being said most of the time, I had to focus really hard in order to make it out. It didn't help matters that the voice you were putting on was somewhat husky; this just made it even harder to understand. If you don't have the equipment to record high quality audio, perhaps you could have seeked out a voice actor on this site. There are plenty who will do it for free. Another option would have been to include subtitles as then it would have been clear what was being said.
I also felt that the animation was rather still. Most of it was just a dog talking, then when the Simpsons popped up on screen all that was going on was a few moving heads. I suppose you were aiming for an angry rant like the number of videos on YouTube, so little animation during the dog talking scenes managed to be acceptable, but you needed to do more in other areas to make up for this as an almost motionless dog against a plain wall wasn't a particularly interesting image to be looking at.
The animation seemed a little too short as well. The dog had a little rant and it was all over. I didn't really get much of an impression of anger from him. Perhaps you could have thrown in a few self-animated scenes featuring The Simpsons or something. I have to be honest, I didn't entirely get what this flash was about and that was largely down to the low quality audio.