Based on the novel by Matthew Quick (an excellent adaption, by the way - if you liked the film you'll almost certainly enjoy the book, and vice versa), this is an original and thought-provoking romantic comedy, but don't let those two words' usual Hollywood connotations put you off.
The actual story centres on two troubled individuals each trying to come to terms with tragedy and mental illness in their lives, and their impact on those around them, who find themselves drawn together despite themselves.
Bradley Cooper and Jennifer Lawrence are both absolutely glorious (Lawrence rightly won an oscar for her performance, Cooper was nominated but lost out, almost inevitably, to Day-Lewis' Lincoln), and the film's worth watching just for these two alone, though the supporting cast is equally fantastic (yet more nominations!). The subtle weaving of pathos and hope with humour and humanity really makes this film stand out. I saw Ruby Sparks at around the same time, too, and I'd put them together as two of my favourite films of the year.
Silver Linings Playbook has become one of my favourite films altogether.