I have some sort of free insurance through the credit card I use for the bill, but if I didn't have that (and god only knows what kind of coverage it is), I wouldn't pay for a plan. The cost and deductibles are high enough that I'm better off just taking the chance that I lose it and have to buy a new one. Unless you have a kid who is likely to dunk the phone in a toilet, I think cell phone insurance is kind of a sucker deal.
For warranty concerns, the phone comes with a one-year warranty and my credit card doubles it to two years (quite a few credit cards offer an extended warranty -- Amex's is fabulous), and by that time I'm likely to be very close to replacing the phone.
v Thank you! I decided to stick with the AT&T insurance since it's a new 5s and from what I can tell that's the best & broadest I can get since AppleCare doesn't help with lost/stolen.