Speaking as a user, the only difference I've really noticed personally so far is that I don't feel like I have any need to hide it anymore. Even as a MMJ card holder, I always worried a bit about getting stopped on the way home, for example. Now, it's legal, so there's no need to worry. I also don't feel like I'm doing anything shady when I hook other people up.
As for greater societal impact? Nothing that I've seen. That'll shift a bit once they get the retailers up and running, but I still bet the impacts will be far less than you expect. My guess is that the biggest thing we'll notice will be people from outside the state coming in for it rather than the locals really changing.