Basically, Nick and Norah's infinite playlist is a cute love story with an amazing soundtrack. Michael Cera plays his typical awkward 'cute' guy who somehow manages to have a wee bit of a female following and Kat Dennings is her own awkward but alternative-cool stock character. The plot summary above is for the book, which the film is based upon. I can say with certainty that there are no stripping nuns (though there is an alter boy with no pants) and no hotel ice rooms (I'm pretty sure there is no hotel in the film at all).
The plot is:
Nick (Cera) was broken up with by his girlfriend Triss who had been cheating on his the whole time they were together, he makes her mix CD's (with titles like road to closure volume 12) and he is in a sort of depression. He is also in a band with his 2 gays friends and their drummer is a childrens toy. Norah is kind of friends with triss and she gets the CD's nick makes. Both Nick and Norah hear about a band 'where's fluffy?' playing in the city that night and they both plan to go. However, it is one of the rarest shows on earth and they have to 'find fluffy' first. Nicks band plays a gig that norah, caroline and triss (with a new guy) attend and this is where they meet for the first time.
Caroline gets drunk and goes missing and it becomes a mission for nick and norah and their friends to find her and fluffy. There's a bunch of weird adventures, references to bands and like i said before, an amazing soundtrack.
It's a love story that isn't soppy, and is for this generation.
Cera and Dennings play their awkwardness well off each other and you can legitimately believe that they are meeting for the first time. 'Beefy guy' is also good for a few laughs and there's a lot of great little odd bits thrown into the film that make it what it is.