Pamela Adlon created a miracle. Semi-autobiographical, which is no guarantee of success. She had to deal with the flak from the early involvement of Louis C.K., which mostly just meant she threw herself into the show even more than before, directing everything, while of course also starring and often writing. She gave us a believable family of mom, three daughters, and grandmother where each character was distinctive. She blended funny and dramatic seamlessly.
I think one example of how well Adlon made the show work is the three daughters. They don't really look related, nor do they look related to Adlon. Yet, thanks to the writing and the acting, they are exactly what you'd expect three sisters to be like. There are no false moments with those three. It's easy to just cast actors that look alike, but to build characters that are real and, to say that word again, believable is v.hard. Adlon did it episode after episode, season after season.
At the end, she said something important: don't feel sad that the show is finished, feel glad that now you can watch every episode on Hulu whenever you want.