most people already have smartphones.. i have one that cost under $50 that has the blockchain.info wallet on it.. i cant see a problem....
but a person having to have a second device that's only function is transferring money. and IF NOT using a mesh network (with its own problems) it would require its own call plan to have internet access.
i think App development is the way forward, not device development for wallets
+1
Smartphones are quickly becoming prevalent (at least here in the US) and already seem to be taking the place of other physical documents such as airline and event tickets and even payments (using NFC). I think we'll see smartphones replacing even more currently used technology once NFC becomes more widespread, and I think this will be great for Bitcoin since people will only need to install an app to use it. Phones are currently replacing other physical devices (cameras, PDAs (lol), GPS's)) and the addition of another physical device seems like a step backward.
I think the future of person-to-person bitcoin payments will be in the form of a NFC-enabled smartphone app. Scanning QR codes is too annoying to be used for everyday purchases but using NFC can be made even easier than using a credit card.