What are you thoughts on marijuana? Are my thoughts correct?

Alright so I have been researching marijuana use cause it looks like a interesting thing. So far, from people I talk to and from articles on the web it seems that marijuana is almost completely harmless( aside from losing a bit of cash and, over time, a small percentage of lung capacity). I saw a video saying that concentrated THC can even surpress growth of cancer cells, is it true? So in short: what are the negetive and what are the positives? And I want real, researched, serious answers NOT bias unresearched prejudice.