I have watched a few seasons of Big Bang Theory, personally I feel that there many other sitcoms in the past that have done better than this, the show usually revolves around the lives of 3 individual, although as the season progresses 4-5 character join the star cast with important roles to play. Now, just because of the news spread very fast that the stars are actually earning 1M per episode, the popularity grew even more. So, just to inform you guys Neil Patrick Harris a.k.a Barney Stinson used to charge 6M per episode.
So, lets come to the main part, although Kaley Cuoco is really attractive and has a special role in the series, but her level of humour can still be considered average. And I guess, we Indians understand about 1/4th of what Sheldon says, maybe even less, which makes even less funnier, now that leaves us with Leonard, Raj and Howard, are usually not funny, they face problem and thats whats funny.
So, overall I would say it is not bad, but definitely not the best.