Sure, they still did stupid things and acted bizarrely, but they also created relationships that acknowledged their unique perspective on life. In fact, the maturing of their relationships throughout the show was one of my favorite parts. This is especially true since [spoiler alert] nearly all of the characters were in healthy marital relationships by the end of the series.
It amazes me that the show has been a part of my life for over a decade. We watched all of the seasons this year at Chloe's request (although her surprise departure left her about five episodes short of the conclusion) and so we were able to see the entire arc of the show's story and characterization. It was particularly amusing to see their reactions to various geekdom fads and technologies as they passed through the decade.
I was also quite impressed with the final season. They came to a deliberate closure that tied in plots and themes that existed throughout the series. They also managed to end with the show still being funny.
Also, the gag reels are worth watching.