I love it, and they are especially great in the Small Format stores that have a smaller selection. I am working on getting all of the team trained on how to use them (we just opened last week). I don't make the guest do the process, I enter the information as they dictate it to me, and have them review at the end, and I insert the payment device with them watching me. The only thing about them is make sure they are charging at night correctly. If the Verifone attachment doesn't work the app will not work, and that is potentially lost sales.
I am not sure if there is a work around for someone with no e-mail, though. I do admit it makes things tougher when they don't have one.