I watched all the episodes of all 8 of the original seasons of Will and Grace. It was so fun. At first I found the constant gay jokes to be homophobic, and it seemed like the gay characters were allowing us to make fun of gay people. But then I just grew accustomed to it and could enjoy the whole thing. The show did a lot to bring queer people into mainstream awareness, and the characters are drawn with nuance so they are not caricatures. Even Jack, the "stock stupid character", has important moments where he speaks about pride and acceptance. The characters are written and played with great affection and respect.
Mainly I love the chemistry between the four of them. I think they are a blast to hang out with and I'm jealous of the actors. I try to pick a favorite but it always changes, because they are all so great and they work so well together.
The last season gets quite serious as it gears up for the final episode. I cried at the ending and thought it was successful. This fall they started a new season, 11 years later, and they ditched the ending from 2006. They just pretended it didn't happen. Even though I was so moved by the ending, I think it was a good choice to have them start fresh.