At the end of the process a Felt card feels authentic. I'd love to write you one if you'd like. Just email me you address.
Felt will never feel as "authentic" as the very premise of the app is to reduce, if not eliminate, the reason for sending handwritten cards.
Some people prefer to hand-write letters and will probably do so until they die. Some occasions require hand-written letters and will probably do so for a very long time to come. (Felt technically is hand-writing so I guess I mean non-digital hand-writing... Do we need to invent a new term?)
I don't think Felt is necessarily trying to compete with the above, it's simply trying to offer a middle-ground between text messages and inked letters. If we look at how quickly communication has changed (some might say devolved) over the last twenty years... wouldn't a product like Felt be a step in the right direction?