I believe it affects you depending on your personality type for sure. This is the lesson i learn whilst high the other night: Your personality type defines how you perceive the world. It is your world. an ENTJ and an ISFP view and interpenetrate the world in such totally opposite manners that it is hard for each other to get an grasp on how they view it!
Weed can make me into an E/I NTJ. It brings out all my shadow functions. It is a totally weird experience. At first it scared me. I see the world through a completely different perspective. If i concentrate on it to much it ruins the high.
However, i can ignore it to a large degree and enjoy all the other fun effects.
I only use weed as a tool for personal growth now. it helps me realise things i miss in my usually living in the moment world.
I believe that what I'm like when i'm sober, is what a lot of people strive to be like when they smoke weed. I don't know if it's just me or other ISFPs who agree with this? but I'm pretty confident in this.
I mean I've been accused of being high so much when I'm 100% sober. Getting absorbed by nature and the squirrels whilst riding my bike and causing me to fall off at the next curb is just common things for me. lol