I enjoy Seinfeld quite a bit, personally. It might be anywhere from 3rd to 5th on my list of favorite shows. Maybe it's all the off-beat stuff that appeals to me, but I know it's not for most people.
I will say that I'm not as crazy about the finale, and I've seen enough forum posts over the years to know that I'm not alone. Certainly, the last couple seasons were not as strong, I believe some writers left after season 7 ended. And if you hadn't watched through the rest of the show (or at least watched enough to recognize most of the witnesses), there is no reason for you to find the finale funny. That whole episode depends on your preexisting knowledge of the show, and it still came off as (relatively) bland.
Now, if you think that Seinfeld's stand-up in all the segues isn't funny, I'll join in with you there. Odd that his stand-up bits are the least funny parts of the show, but perhaps not when you consider that his character's comedy was not identical to the material that Seinfeld himself used to use.
One last point of agreement, and I'll stop typing...there are a dozen or so episodes that I don't like to watch. Sure, those episodes exist in M*A*S*H also, but only in cases where the writing simply struck me as poor (Exorcism, April Fool's, Trick or Treatment, and Oh, How We Danced are a few examples). But in Seinfeld's case, it is the subject matter (like "The Contest," perhaps the most famous single episode of Seinfeld) seeming unpalatable, unacceptable for network. For a show that experienced so much success in spite of its lack of short-term or long-term plot, writing about certain risque habits still seems like awfully low-hanging fruit.