In my experience while alcohol can make you very uncoordinated and has the so-called 'liquid courage' effect, cannabis tends to only make the consumer enjoy what they already enjoyed more and differently, and rant about whatever ideas pop into their head. The first time I got really drunk, I had to be walked home and put in bed, then overslept and had a terrible hangover. The first time I got really high, I thought I was in a horror movie for half an hour, then played video games with my friends and had a religious experience listening to music and watching the iTunes visualizer. Cannabis in my opinion has less potential for both harm and abuse than alcohol.
Marijuana is safer than alcohol by the numbers, but there exist a few select cases wherein marijuana expresses itself as to not be for everyone. Like anything else in the world it's not perfect, but yes its much more safe than alcohol in general. More research is definitely needed.