Aside from the yucky, disgusting … drooling-over sexual mates parts of this show; a few poorly-chosen ideas that created contradictory events intended to elicit some tension or some cheap comedy; and maybe a weaker (season 7)…
I think this is a brilliantly crafted show.
It is funny; the scientific/nerdy dialogue is masterfully written; there is a remarkable amount of general information & general knowledge in various subjects; there is an actual storyline (not just some random events & random acting); the characters’ development is evident yet seamless; the acting (hence the casting) is superb; it got stronger as it evolved with more characters & more dynamic - which means that the creative juices that formed the show initially were still very much engaged; and lastly - the audience grew fond of the characters, riding the rollercoaster of events & emotions with them.