TBBT summed up.
The earlier seasons are comedy gold. Season 6 and 7 are also good and worth watching. Season 8 is the weakest season, the one I skip every time. Season 9 it starts getting good and is nice and again worth watching. Season 10 is again very nice. Season 11 was surprisingly too good and better than the previous two seasons. Season 12, the finale season was however weaker than 11 and was a bit disappointed since I had high expectations after such a good season 11. The final season had some good episodes but there were a significant number of not so good/ funny episodes as well. The last few episodes however were amazing and the show finally ended on a slightly controversial but otherwise fantastic and wholesome series finale.
When I first discovered the show, I cannot express enough how much I loved it. I watched every episode at least thrice on my first viewing. I was around 16 and used to eagerly wait for the next episode. This show made me laugh like no other show ever. My family members would walk in and occasionally watch it too and commend me on having such a good taste in shows lol.
However I see a lot of people complaining about the show being the worst sitcom, etc. Maybe it's an adult thing, where they're just too irritable, being worn out with life. But as a 16 year old having no responsibilities and being so chilled I enjoyed it thoroughly. Now I'm 25 and haven't watched it since a long time so don't know how I'll feel about it now.
Anyway I was just reminiscing my teenage days lol.