It's a new show; it's still got some kinks to work out, and I don't completely disagree with any of the previous reviews. The characters aren't well developed (yet), and, yes, some of them are essentially caricatures, especially the promiscuous male neighbor.
However, I think the previous reviewers who dismiss Cox's character as a vapid, sexually charged woman have somewhat missed the point. The show is not really about love or sex; it's about women retaining their feminine identity despite society's insistence that middle-aged women are past their prime, and about dealing with the societal prejudices that come with being a middle-aged woman (some of which can be seen on this very board; more on that later).
Jules is recently divorced, and is suddenly plunged into the single woman's dating world as a 40-something. The show is attempting to capture (with admittedly middling success), the panic and confusion that accompanies the single, middle-aged woman, as she competes with women half her age for the same men. Love? Sex? Never mind all that; Jules would settle for having some fun -- and doesn't she deserve it, after being a mother and housewife for so many years? The show extracts its humor from the awkward journey middle-aged women must often traverse, from motherhood to single-hood, and through whatever else is along the way.
This is where the neighbor's one-note caricature becomes necessary, or at least makes sense. He exists to contrast the different societal attitudes towards middle-aged men and women. Men easily rejoin the dating scene, but women are met with harsh sneers and judgmental assessments. Even in the reviews here on IMDb, some of the people complained that Jules was a sex-crazed maniac, an idiot nymphomaniac, and whatever else, despite that she waited until the tenth date to have sex with her boyfriend. A woman who waits until the tenth date is sex-crazed? No, she just wants to have fun and feel desirable, just like the rest of us.
That brings us to the show's problems, and it has a few. Cox is far too attractive to be convincing as a desperate cougar, for instance. And yes, it would be better if the other characters were more interesting, and if neighbor were more than just a one-note cad. But the show is, in my opinion, still quite funny, and the characters are becoming more sympathetic, even Jules's do-nothing ex-husband. I think the show has a lot of potential, and I will continue to watch it.
As I recall, Courtney Cox's other show, Friends, was almost unwatchable in the first two seasons. But there were good elements there, and eventually they figured it out. I suspect they'll do so with Cougar Town as well.