where the fuck were you that it smelled? I mean granted there's a huge amount of weed-smokers but they don't do it out on the streets, maybe in their cars but not anywhere else public.
I've never seen illegal activity but berkeley is kind of ghetto and in front of the lawrence hall of science they have a rape button you can press since it's on the top of a hill and pretty remote and takes 5 minutes by car to get up there.
however if you like berkeley, there won't be any major problem.