First of all, let me tell you something about myself, to make sense of my evaluation: I am eighty. I am a European (not a U.S. citizen). I am a Muslim convert. I just got the first TV intended for my own use (there were two previous TVs in my life: the first for my daughter, in the sixties, the second for my husband, in the eighties & nineties; that is when I watched a few programs with him: Startrek (the second wave, not that stupid first series, and certainly not that jingoistic last production, the "prequel" which suffered greatly from being made right after the attack on the twin towers. I am not a TV watcher, not so much because I don't like what is on TV but commercials (and perhaps capitalism in general) make me nauseous. I don't think there is anything on TV I ever would give five stars to. And although I now have a 60-inch monster, I have used it exclusively to play DVDs and tapes.
I don't think the characters and situations of "Little Mosque" are particularly unusual. But since the show deals with issues that have that have also irked me at my own mosque--for example, the totally unnecessary sexism coming from the various Muslims' ethnic culture (totally unnecessary in the framework of Islam and its founder). I feel relatively well represented by the character of Rayyan. I assume that Sarah is a Muslim to please her husband, or more likely in an effort to appease her unappeasable mother-in-law (I had one like that; she got herself a larger apartment on my wedding day so that my husband could move in with her); since Muslim men are allowed to marry anyone of the opposite sex, even atheists and scientologists, Sarah had no need to convert; and I consider her, at best, a Muslim in name only.
The first season was quite pedestrian, but it established characters, and rounded them out somewhat. Seasons two and three, I might give four stars to. (Just to establish what I might give five stars to Satijit Ray's "Music Room", or to "Rasho Mon"--or "The Battle of the Casbah," for its political relevance to present-day U.S.A.; I cannot think of one TV show I would give five stars to, even though I might have enjoyed them (I have also watched "Startrek: Next Generation" and "L.A. Law" because my husband was watching them).
Getting back to "Little Mosque", I am going to watch tonight season 6, disc 1: I am feeling not that the show is running out of steam, but that it already has done so. There are fewer characters. I feel that Reverend Thorne is a pointless monster, totally two-dimensional, while his predecessor is a human being. Baber at least has ability as a mathematician / statistician; for example, when he taught at his daughter's highschool, the students actually liked him so when Islam is not involved, he can be rational, even witty; and since he is not a specialist in humanities or social sciences, his religious rigidity appear logically justifiable.
So I would call "Litte Mosque" a somewhat shallow (but not stupid) entertainment, floating somewhere between two and four stars: that would make three stars a reasonable compromise.