Having seen the first three episodes of Season 2, I'll just say that they are fantastic. I won't blow it for anyone by giving away spoilers, but let's just say they really up the ante and eliminate a lot of the soapy stuff that was holding the show back at times during Season 1.
Clearly the producers and writers understand that they have a limited window in which to tell the story they want to tell and aren't holding anything back in Season 2.
I think even people who missed all or most of Season 1 can get into Season 2 without trouble and enjoy it. They explain everything up front and the basic outline of what's happened so far is not difficult to follow. I would highly recommend watching the Season 1 episodes online at CBS.com though as mentioned above simply for the chance to see some great drama.