The fact is, FF is nowhere near as brilliant a show as its most ardent supporters claim. It has a scattershot approach, trying to be too many things at once (sci-fi/western/comedy/action/adventure/commentary/whateverelseyoucanthinkof). And without question, it's rough around the edges.
That being said, the strength of the show is the camaraderie of the characters and the humor. Even when the characters are at odds with one another, it's rarely played for cheap melodrama. And the humor can be absolutely hilarious -- but here, too, you have to be open to some of the darker humor from Whedon. There were times when I laughed out loud and, others, when I though Whedon was simply being a juvenile prick.
But given that the series only has fourteen episodes (and one movie), it's not a major investment of time to rent (or even purchase) the show and watch it. It's definitely one of those shows you just have to jump in and watch and decide for yourself whether or not it suits your taste. Despite its obvious flaws, it definitely has value.