I agree. Going to class is mostly a waste of time for me as well. If I do go, I just end up goofing around on the internet during the lecture. With that said, there are some classes/teachers that do make it worth your while, so keep an eye out for those.
When I don't go to class, I usually just read the notes, and skim through the ppts quickly. I only listen to the lectures if I found something to be unclear but other than that I rarely do. I do pretty well on exams, and with this approach I am studying less than I was when I attended all the lectures in the beginning of MS1. I do sometimes miss questions related to minutiae, but who cares?
But, as I have been hearing lately, it seems to be a good idea to start incorporating standardized review books. I am going to start using FA, RR Path, and also ANKI for the upcoming classes. I am still a MS1, so take my advice with a grain of salt, but this approach of just using lectures to clarify material as needed works for me.