Loved the first 2 Seasons-Can I jump in now

I saw seasons 1 and 2 but due to work and being on opposite other shows I loved, I didn't watch seasons 3 or 4. So the question is: Can I jump in when season 4B starts Wednesday, or should I try to catch up on Hulu first. Obviously, that's not going to happen by Wednesday. (20 hours of it!) What do people who watched it all think?