I don't use it, but IMHO it should be legalized, because as others have already said, when abused it's not as bad as alcohol, which is legalized in most countries.
Alcohol and tobacco are already legalized like forever, so you might aswell also legalize marijuana and earn tax money from it.
Here in Germany it won't be legalized in the near future. From what I understand the "beer lobby" is very strong in Germany and they fear that legal marijuana would compete with beer as a recreational drug (although 99% of Germans wouldn't call beer a drug), especially with younger people. So they fight it off with everything they have.
I actually find it quite fascinating that some states in the US already legalized it, because compared to Europe the USA are considered very conservative (alcohol only after 21, almost no legal prostitution and gambling, abortion debate, etc.).