I think that the hype of the finale is what has disappointed most people. I found it thoroughly amusing and found myself laughing a lot. I think it actually would have been better if maybe Jerry Seinfeld asked NBC not to let word out that he wanted to end here. Maybe if we didn't know it would be the last new episode we'd ever see, we would have just viewed it as a new episode and found it amusing. Too much hype went into this. I don't know about anywhere else, but in Boston they actually had a countdown clock on the NBC affiliate and since it was announced they were ending, they had the entertainment reporter tracking down anyone who might have known Jerry Seinfeld. It's a lousy news station anyway, more tabloid, but it was really ridiculous. They actually went to Tom's Restaurant on the final night and interviewed anyone on what they were going to do now.
I think it ranks up there as one of the better series finales with the exception of Newhart, which will always remain the classic, and the Mary Tyler Moore show. I know it's been compared to the Mash finale which I found the most depressing show ever. That was a sitcom that lost track and the whole suffocating the baby thing was really in poor taste. But this is just my two cents.