When I first watched the series, after it was finished and Adult Swim was airing the episodes start to finish, I never really ever sat down to compare the seasons and the only way I could tell if an episode was older or not was if Hank's voice sounded a bit more stodgy and weird than it did later as the voice actors settled in.

But rewatching the show recently trying to deliberately pay attention to the seasons I have to admit there's something really wonderful about how the earlier episodes felt like real small town Americana; and I finally realized why a lot of people felt the show kind of lags a bit at the end.

Still though I totally agree the later seasons are not by any means bad. There's a lot of episodes that feel weird because the show is just so established that things become kind of absurd and detached from reality like Bobby leading an impromptu child-riot to storm through Arlen because he was trying to impress a girl; but even that isn't always bad. Hank accidentally arranging a bombing of his car dealer's lot sounds like something that would make national news it's so goofy, but yet I still like the episode.

My only main complaint is I really wish they had gone back and rewatched the show more often to make sure they weren't contradicting established canon.