A difficult question, because it depends very much on taste. Anyway, I'm in the camp that considers novels doing more harm for settings than doing them any good. Plus, although I'm a big fantasy fan, I don't like most of the fantasy novels, because they are often pretty bland.
Nevertheless, I consider the FR to be one of the best settings around, because it's just the right mixture of playing out stereotypes with many elements that makes them interesting but familiar at the same time. It does many things "right".
1) It's a modern setting. Yes, you have wizards, elves, nobles, but they are just there for the icing. The society of the FR is modern, with modern ethical standards and urban centers that resemble modern cities in their organization, just without cars but with the occasional "magical shoppe". They are definitely not pseudo-medieval, there is no hint of a feudal society, and except pseudo-Egyptian Mulhorand there is no carbon copy of historical places. This modernity makes it easily accessible to everyone.
2) It's playing on nostalgia. Villages in the FR have a certain feel of the 1950's to 1960's to them (though more American than European in style). At least older gamers may have a soft spot for this scenario, and even younger ones know this from TV. The core of the setting, the Heartlands and the North, have a very coherent feel to them, which resembles the Wild West of the late 1800's, though more specifically the version of pre-1970's TV westerns. The American Indians are replaced by orcs and goblins, which makes it perfectly politically correct. Both aspects make the setting accessible and in a nostalgic way enjoyable at the same time.
3) There's the fantasy effect, of course, in all its escapist and entertaining facets. You have lots of Tolkien references that everybody knows, like wizards with pointy hats and elves with pointy ears. However, those wizards don't have very much in common with a Tolkien wizard except this pointy hat, and elves don't really play the role they represent in LotR (no big elvish powers). It's a similar thing with lots of other fantasy stereotypes the FR draw on: they have a very nice twist that makes them interesting and playable. This is a very clever point: drawing from a common memory among most people makes the setting easily accessible, although a closer look makes clear that these memories are most of the time heavily altered. The often heard claim that the FR are a mere copy of "standard" fantasy forgets that the FR actually defined many of these standards.
4) Diversity. Yes, this is often mentioned as a drawback, but i really don't understand that argument. There's no force that prevents anyone from sticking to the Sword Coast or the North for his campaign(s). These are options, many options, and you are allowed to pick one or as many as you like. The villains are interesting. Zhentarim, Red Wizards, Malarites, all of them are great concepts for exciting villains who can keep your campaign on its way for ages. If those bore you, you probably don't use their potential.
All in all, these four points do it for me. Yes, I also have "my homebrew". However, I'd happily play a FR game if opportunity strikes

.