After the first three episodes I thought: "Wow, this is an instant cult classic!" It's just about drinking and the glorification of alcohol is incredibly hilarious.
But... I don't know... maybe the writers panicked half way through, that they created the perfect drinking-comedy and so, for some reason, they unfortunately HAD to add stories for each main character to add some drama. And those stories are pretty generic and not even that good.
From there it's still funny, but the (sometimes very) serious undertone in the second half of the 1st season just doesn't fit to the outstanding start.
