I hate sitcoms (Silicon Valley and East Bound and Down are more my taste for comedies), but I think I have watched every BBT courtesy of TBS reruns. I have no idea why, because I don't think the show is that good. That said it is no worse than the majority of other sitcoms. I would actually said it is better (at least early on), because I can actually finish an episode.
Also Sheldon is the one thing I actually like about the show. I really can't stand the most of the other characters. That said I have always watched the show with the understanding that he has Asperger's. True or not it works.
Even though BBT sucks I think most people would agree the the women on the show are WAY better than the men.
Bernadette, Amy, Penny >>> Howard, Sheldon, Leonard and Raj.
This is 100% wrong (well subjectively). Bernadette is one of the worst characters on TV. She is awful to Howard, and a complete bitch to her friends. She would make a good wife for Ramsay Snow. The only one worse is Raj's unbearable redheaded new girlfriend.
Also the addition of Bernadette and Amy to full time cast members has pretty much made the show un-watchable. BBT at it's best (which is not that good at all) is when it focused on the 3 main characters (Penny, Leonard, and Sheldon) with Raj and Howard randomly showing up. Now that they are up to 7 regular cast members, the show has dropped to the bottom of the toilet.