Season 1 was a pretty mediocre slice of life with annoying characters. It had no clear direction (other than it clearly being about the creator and her husband), and failed to use a lot of the characters. Remember Marco's friends? No one does, because Marco isn't a person; he's Nefcy's prize. 6/10
Season 2 almost went somewhere but devolved into everyone obsessing about Star's pussy. 7/10
Season 3 was probably the most fleshed out, with the most interesting episodes, although by then it had lost some of its whimsy. It was still probably the best season, unless you're one of those faggots who insists season 1 was the best because it still hadn't developed enough of an identity to challenge your autistic projections on what you wanted it to turn into. 8/10
Season 4 dragged its feet early, meandered without a clear goal, and had trouble establishing a central theme or point to its own continuation, in addition to punctuating the whole series with a laughably stupid and poorly thought out conclusion. You could definitely tell it was a thrown together season. The poor writing could be forgiven if the ending had been satisfying, but it jumps over all logic just to get to the final imagery of a magic Earth, and Star finally with Nefcy's Prize. 5.5/10
So, overall, probably a 7. Much like Eclipsa, Nefcy is too self absorbed and obsessed with the world seeing how perfect her husband is for her and only her, despite him being sooo desirable by soooo many other women. Her projection fantasy simply got in the way of too many elements of the story.