I love this show. Finally a show about us real geeks/nerds. My only criticism is the lack of representation for female geeks(they have scientists, but none that are into speculative fiction, comics, gaming etc.).
My favorite character is Leonard; he's practically a white male version of me, but I have way better communication skills, I'm a lot less awkward, and I'm a goth.
I have a love/hate for Sheldon; I don't know whether I should find him more hilarious or punch him.
Howard and Raj are so funny together. Their strong gay subtext(that everyone in the show has commented on at least once) had thinking they might get together, but gay nerds would probably be too much for mainstream TV.