Best Season of BBT Sheldon Cooper is unavoidably the king of the show - the massive black hole this Universe revolves around if you will. A child prodigy, now a 24 years old theoretical physicist PhD with absolutely no social skills or known sexual drive. Sheldon may be on the verge of unifying the fields but cannot drive a car to save his life or break a smile even remotely resembling that of a mere homo sapiens. His equally super-intelligent (yet sexually confused girlfriend), Amy Farrah Fowler, (which Sheldon finally claimed) received a far more enlarged role this fifth season. However, she was not a very good addition and she unbalances the show. Her character only manages to blur the focus form Sheldon (there is only room for one idiosyncratic genius!), diffuse a number of comically charged situations and gum up the show's flow.
Leonard Hofstadter is Sheldon's roommate and primary ...keeper. An experimental physicist himself (who Sheldon tries to "help" by steering him towards a teaching career), he juggles Sheldon's idiosyncrasies with his personal neurosis - not to mention his crush on his neighbor Penny. Which crush, like lunar eclipses, follow a predicted yet unavoidable periodicity. Leonard tried his hand in a long-distance relationship this season with his friend Raj's sister, Priya, but he seems to be gravitating back towards Penny once more.
Howard Wolowitz is the only one with no PhD (and Sheldon will never let him forget it). An engineer (whose crowning achievements were a mechanized arm that is used in the space shuttle and a liquid waste management solution), he also managed to wreck the Mars Rover in hopes of landing a girl (but he made sure no one can prove anything). The fact that he is a short man with a severely outdated and misguided sense of fashion, still lives with his mother, insists on using a collection of pickup lines straight from men's magazines advice columns - and yet carries himself as God's gift to women is just hilarious. Howard used to be the show-stealer. Whenever he entered the scene you just knew he would offer such an outrageous perceptive that would render you speechless. Now, if only Howard's character was allowed to continue in its stellar trajectory. He has been weighted down by his fiancée, Bernadette, who is very likeable, but also is cramping his style. Not to mention that she, slowly yet inescapably, is turning into his scary mother.
Rajesh Koothrappali is a particle astrophysicist with a fashion sense close to absolute zero and a severe case of shyness - to the point that he cannot speak in front of women unless inebriated. He keeps using the "poor Indian" defense although his father is a rich doctor who drives a Bentley. His character, even in the fifth season, remains underdeveloped.
Then there is Penny. She is the proverbial good girl next door who came to California with stardom aspirations but so far works as waitress and suffers a sequence of bad boyfriends (Sheldon has in fact calculated the exact number of them, extrapolated from a bell-curve that started at 14)- and, obviously, from her neighbors. One of the best fifth season moments: slipping in the "Who is the greatest?" cheer between Sheldon's patented knock of repeated "Penny!".
The show unavoidably makes use of previous sitcom combinations (the odd couple, the unfulfilled love-interest mismatch) but even if one manages to discern them they are used in such a fresh manner that all that is left is great entertainment!
The way to truly enjoy this is to own it on BLU-RAY.