Most started watching "the Show About Nothing" in the series' middle years, but I believe that 'Seinfeld' was at its best in the begining, although it remained the greatest sitcom of all time until its end.
'The Jacket' is a great example of the overall greatness of the first few seasons. 'The Jacket' is my favorite episode for many reasons. First of all, it introduces us to Alton Benes, Elaine's dad, an imitading presence whose effects are felt by the veiwer as well as Jerry and George.
Second of all, who hasn't been able to relate to Jerry's story about getting something new and not being able to put it down or take it off?
Now, this is a sitcom, so comedy plays an important part in this as well. It's full of funny moments, both obvious (like George's constant singing, another relatable story) and subtle (like Geroge grabbing Jerry's sleeve, only to have it yanked away). Kramer's story plays a part in the main story in typical 'Seinfeld' fashion, and the ending is just hilarious.