I loved the show, particularly the first six seasons. It was so witty and literate - the one liners were amazing. And of course, there was the fun chemistry between Sam and Diane. I thought they handled the transition to Rebecca well, too. But the showrunners changed after season 6, and it was never quite as consistently funny again, though there are certainly some gems in the later years. I also didn’t like how in the later years, the characters became more one dimensional - Carla was meaner, Sam was dumber, Rebecca became a shallow, emotional mess, etc.
But those first six season are real classics.
Also, I think poor Shelley gets tagged as an awful person, and she really wasn’t - at least not according to Ken Levine, one of the producers:
Now let me say a few words about Shelley’s behavior. She could be difficult. She could be obstinate. She could over-think something to death. But it was never out of spite. It was just her very exacting process. At times I will admit it was frustrating. And exhausting. But Shelley has a good heart. She is a sweet person. And in her defense, she had an incredibly complex difficult character to play. To make Diane Chambers loveable and funny while still maintaining her haughty attitude took a very special actress. It would be so easy to just hate Diane. Shelley did an extraordinary job. I can't think of a single actress who could have done the role better... or even as well. So if it took her longer to find the moments and just the right shading then tough. The results were on the screen.
But the point I want to reiterate is that she is a lovely person. I know actors who are just mean-spirited monsters -- unhappy miserable people who want everyone around them to be as unhappy as they are. That’s not Shelley.
http://kenlevine.blogspot.com/2013/09/did-shelley-long-try-to-get-kelsey.html