Portlandia is starting to reach the end of its string. It's still got some good moments, but those moments are rarer now. Much as I love urban hipster culture, there's only so many times you can go back to that well and still think it's funny. We've watched just about all of the season now, and may or may not finish off the rest of it. With our move to Los Angeles, we've dropped it, and I think it's somewhat unlikely we pick this up again.
Anyway, it's not hard to watch this show, and if you're still entertained, stick with it, but I'd definitely start in Season 1, and you'll know if you want to see season 3 when you get there.