The show fell off after it drifted too far away from it's original theme.
It was originally based on Hamlet.
Once Jax was no longer conflicted about the direction of the club and embraced everything it stood for..........it didn't seem as interesting.
Also, the show wasn't the same after Clay got killed either.
Couldn't stand him, but the constant underlying conflict between him and Jax was a crucial part of the show.
Once Clay was gone, there was nothing similar to replace that dynamic.
I started watching the 1st season again sporadically...........simply because I didn't start watching the show when it originally aired until more than halfway through the first season.
Can't see myself re-watching the entire series multiple times like The Wire though.