I should probably start with a health warning - New Girl has one of the most annoying, twee and self-congratulatory opening credits that I've ever seen. I mean, they're truly awful, and I think even the show knows this because it cuts them down as often as it can. They sum up a sort of "Darkest Possible Timeline" version of the show, where Deschanel's character Jess is peppy and kooky and loveable and makes the world better by just being peppy and kooky and loveable and the rest of the cast hang around her being made better. Indeed, for a couple of episodes, thats what it looks like you're going to get, but thankfully, it shakes it off pretty quick.
The "sit" in this case is that Jess has split up with her slacker boyfreind and needs somewhere to live; and the other three characters; Winston, Nick and Schmitt, need a fourth room-mate. So Jess moves in, and comedy ensures. And oddly enough, it does. The main friction in the show - the thing that most of the episodes spring from - is the conflict between Jess' enthusiasm and Pollyanna like enthusiasm for making the best of things, and the messy reality of growing up and being smacked around by real life. Nick as just come out of a long-term relationship and is drifting, unfocused through his late-twenties. Winston is just back in the country and trying to re-connect to well, everything, and Schmitt is a preening hound-dog poseur.
Over in the Darkest Possible Timeline, this is a show where a problem occurs and Jess makes it better by being peppy at it, a sort of hollow star vehicle that trades solely of Deschanel's Manic-Pixie-Dream-Girl charm. But to it's credit the show realized quite early that if you're going to care about these characters, then it can't be that simple, and Jess' attitude is wrong as often as its right and whilst still clearly "the star" of the show she's not the character around which all the others orbit. It lances the shows biggest potential problem and lets its wider cast florish.
Its fair to say that New Girl isn't the funniest show we've seen recently and we haven't burned through episodes in the same way that we have with say, 30 Rock. It is charming, and at its best when it goes for high-tempo farce, with the sort of running around and rapid-fire dialogue that just carries you through any silliness in the setup. It's not edgy, nor demanding, but solidly, safely, funny. What more do you want from a comedy show?