We use our debit card for everything except renting a car. Most car rental companies won't take a debit card. Some might but most won't so that was the only thing we needed a credit card for. Everything else, with the exception of using cash to buy from some of the food carts, we used our debit card. Not once were we asked for ID of any sort and most of the time they didn't even look at the signature on the card. They scanned the card then gave it right back to us before the credit slip was printed.
If I'm not mistaken, I believe they take your debit card and use it as a credit card because I don't recall any of the places asking us to enter a pin number.