I enjoyed it at the start, but the quality definitely dropped off around season 8 or 9 when they announced that there would be a known number of additional seasons. It did get better again toward the end, and I think I watched every episode, but I never bother watching the re-runs even though they're shown often. I think my interest also waned when I read that the main stars were getting $1 million each per episode. Many of the later episodes had run times of under 20 minutes to fit in all the advertising, and I couldn't help remembering why as I watched. The highest paid soap stars here only earn ยฃ250k a year, so it's a bit of a culture shock.
Another issue I had was that after the first few seasons, the team of writers obviously could not comprehend that people like the four male leads might spend long periods of time single. With the exception of Sheldon, the others spent quite a bit of time in relationships. Maybe they should've watched the trailer a bit more often.