I haven't watched the OC before, and was wondering whether it's good and should watch it? I know fans wills be biased so could you give reasons?

You should definitely watch it.
I personally believe that it has good story lines. It is hilarious. and you can watch the episodes over and over again and not get bored with it.

Yes, it's good, though I liked it before Misha Barton left after Season 3. She wasn't my paborito as Marissa Cooper but still the ipakita was better with her in it. Season 4, in my opinion wasn't that great but maybe you might like all seasons.

Thats a good tanong and its okay asking this:) I can personally recommend you The OC especially seasons 1-3 with original cast, relationships & story lines which are the best. Its definitely ipakita worth of watching, because there is a lot of fun but also a good drama which good ipakita needs. Ryan & Marissa and Seth & Summer are just great! Very good teen ipakita of its times, its just a pity it reached only 4 seasons. i heard that the atmosphere on the set wasnt that good anymore..