My major concern, which may kill the show for me in the long term is that the Leonard's character has been reduced to an "interpreter bridge" betweeen the Sheldon character and the rest of the world --- the character no longer stands on its own.
Also, lately they had some dull episodes, with 2 of the 4 guys having (being locked down by) girlfriends.
Sheldon is the funny guy in the pair, and Leonard is the straight man. That dynamic was even in the first episode.
What made Leonard more interested before was his quest for girls/Penny. Now he has Penny, he is a less interesting character because he has no point of view driving stories.
Also, lately they had some dull episodes, with 2 of the 4 guys having (being locked down by) girlfriends.