Great debut season, 2nd season practically perfect, 3rd season excellent but you can already see some drop when the episodes focus on the romantic side (Leonard-Penny/Wolowitz-Bernadette) , 4th season, with invasive love plots, random use of various characters (Raj wandering aimlessly, Sheldon on the verge of becoming a caricature, Wolowitz now stuck in a storyline that has nothing to say), was painful. I still rate it a 5 with hope for a revival.
more
