Yep i got one.
Bluetooth link it to ya phone and take payments.
Its good but relies on 3g! most time waiting a door step was 2 mins watching a circle spin :/
What is good is you can genuinely take card payment on big jobs. Just remember about the fee!
I have managed to blag to jobs on the fact they can pay by credit card.
Battery life is an issue BUT i learnt a neat trick from PAYPAL.
For £50 its well worth it, as no monthly fees