Understand this with SquareTrade (I was looking into it myself for a while)
1. Does not cover theft
2. Will only cover up to $399 (16gb) and $499 (32gb)
2a. This means that if you bought your phone for 32gb for $299 and had to get it replaced through squaretrade for accidental damage, they would reimburse you $499. Subtract the $50 deductible, and the $115/2year insurance rate, they are actually paying you $335 through insurance. Combine this with the fact that you have to pay $699 to get a new phone (usually, unless apple/att agrees to make you sign another 2year contract for $499, which is not guaranteed by any means). This means you actually have to pay a total of $365 for a replacement iPhone.
3. I believe it is possible for you to insure the phone for $599/$699 but only if you purchased it for those prices (since they require a proof of purchase)