I gotta go with the concensus here. If the DM makes a point of targeting dependants, avoid familiars at all costs... but on that note, play a monk and avoid getting too attached to your gear, because such DM's are fond of whittling down your characters, so prepare for a poor, lonely game.
For anything else, though, familiars are easily worth the cost. If your DM doesn't cheese and allow enemies to automatically know that that specific animal is really a familiar, you get a free Skill Focus and a talented scout. Or else it can be a fragile bit of "gear" that adds two feats. Depending on your playstyle.
Also, for people who seem down on familiars and multiclassing; the only things a familiar stops gaining when you multi out of wiz/sorc is its intelligence, natural armor, and special abilities. Its saves, BAB, hit points, and skill ranks are all still based on yours, and since it's hard to get worse than those values than a W/S, multiclassing is a little more even, at least as far as the familiar is concerned.