This show is a guilty pleasure for me; I can't stand teen dramas, but this one rises above them all because of the occasionally hilarious and snarky writing, plus a cast of really great, likeable characters--well except the lead guy, Ryan, who seems like he only has one expression plastered to his face, the wounded dog expression. Don't like him at all.
IMO the best character here is Seth Cohen, played by Adam Brody, who gets to say the snarkiest lines ever; I've read that Brody adlibs most of his lines, which makes them even more hilarious. His recurring love triangle with Summer and Anna is the one to watch, not the angst-ridden crap of Ryan and Marissa.