As Donna pointed out, this existing thread pretty much discusses this topic. Pity to have two threads on the same subject.
But to your point, AJL, as someone who abhored Rabin and hasn't missed him for a second, nevertheless, ends do not justify means.
How would you like it if anyone who hates a politician goes out and assasinates him? There's no end to such a potential collapse of society.
In addition, as a staunch anti-Rabin person myself, he was not a dictator. At least no more than any other Israeli politician. Maybe the word you're looking for is demagogue. But then so was Barak and so is Sharon, in my opinion.
Of course, the bottom line is whether Yigal Amir is the one responsible for Rabin's murder in the first place. Again, that should be discussed on the Rabin assasination conspiracy thread.