A film that stars a bunch of people you’ve probably never heard of and that’s quite explicitly a romantic comedy is not one that would normally be cause for much excitement.

Romantic comedies – in fact, comedies full stop – rarely seem to get the critics too excited. It’s been ten years since anyone got an Oscar for starring in a romantic comedy, and that was Jack Nicholson, one of the most award-laden screen actors of all time, for As Good As It Gets, which ticks all the Oscar boxes of having a lead character with a handicap struggling against adversity, and in some ways isn’t really a comedy at all. Jack Nicholson getting an Oscar nomination is much like the sun coming up – it’s to be expected, no matter what the material. The general trend of awards shows for the last several decades has been to entirely ignore the romantic comedies unless they are directed by Woody Allen.

In other words, the almost unprecedented excitement revolving around Knocked Up should be enough to make you sit up and take notice, even if the words “romantic comedy” normally send you scampering for your Steven Segal box set to cleanse yourself of the chick-flick vibes. Critics in the States have been pretty much unanimous in their praise, with even the mighty Time magazine – normally so keen to avoid hyperbole and appear measured in its take on anything – lauding it as “a small but welcome miracle”, and the equally high-minded New York Times dubbing it “an instant classic”.

So why all the excitement? Considering that all romantic comedies revolve around “boy meets girl, boy and girl argue, boy and girl fall in love”, what have the makers of this latest addition to the genre done to elicit such rampant praise from people who have surely seen more than their fair share of this kind of movie?

The thing is, from a plot synopsis – and even from the trailer – you’re really not going to be able to tell. Guy meets girl, guy and girl have a one night stand, girl gets pregnant and gets back in touch, guy and girl try to make a relationship work for the sake of the child, despite hardly knowing each other and having very little in common. From that summary it could almost have been made by the American League for Decency and Family Values (if such a thing exists, which it probably does), and hardly sounds like much fun.

Yet though the positive, pro-family message has no doubt pleased many of those who normally attack Hollywood for its lack of morals, it is the humour that’s really reeled them in on the other side of the Atlantic. Written and directed by the chap responsible for The 40 Year Old Virgin, if you’ve seen that recent hit comedy, you’ll know that despite the fairly standard-sounding premise, up-and-coming writer/director Judd Apatow has a knack for finding the unusual in the mundane.

Whether you too will find this an instant classic will take a trip to the cinema to find out. But movies rarely get this much positive press – it’s practically unprecedented for so much positive buzz to appear around any movie, let alone a comedy. And that’s got to make it worth taking the risk, surely?