From my experience, if your bike is worth less than $200, thieves are going to be incompetent and a decent chain/U-lock can stop them easily (they might try to steal something detachable, though). If your bike is worth enough, a determined thief can get trough anything, so keep that baby safe in your home.
We get a lot of stolen bikes in our mid size city, but the percentage of cheap cable locks used is too damn high. It doesn't help that asking what kind of lock was defeated is in bad taste and no one is asking that question when someone is looking for their bike back.
I think that the inability to police such theft is basically robbing the planet of a better future, since getting an electric bike and expanding your green transportation capabilities is not really advisable when the bike can go missing so easily.