Although later episodes had plots that could be described as Altman-esque (multiple storylines that interweave in unexpected ways), it never lost it's edge (IMO, I'm sure others will disagree).
I'd call it a show people either loved or hated. I was in the latter group -- I just never got it.
I loved it. I must confess(darned American Solipsism) I thought he was kidding. I feel terrible, now!
I hated it. Except Kramer.
I hated it all.
Thought it was clever but unengaging.
Another in the hated it category. It was a show about people I would hate if I ever met them in real life, and it didn't give me a reason not to hate them in fiction, either.
And I never saw the point in paying attention to people I hate; even laughing at, not with, people like that is a waste of my time.
I think you were more likely to love it if you were a New Yorker.
I was also a sucker for the show's guiding principles: No hugging; no learning.
I also hated it. I thought they were all mean, mean people, and I have enough mean people in my life without watching them on TV.
Liked the show until Susan's death, which was treated so callously I couldn't like the characters after that.
Oh, man. I've felt so alone in my Seinfeld hate.
It disgusted and failed to amuse me.