The one review I saw on Amazon was pretty bad, that in itself shouldn't put you off completely as Amazon reviews cant always be trusted but it did mention a few very specific issues with it.
http://www.amazon.com/HiTi-Digital-Mobile-Studio-Printer/dp/B003LZUPP6
Just looked at the cost of media for it and that's a bit disappointing too, would have to offer a nice saving over my current costs for me to give one a try but at the costs I saw it doesn't really offer any advantage.
I am always on the lookout for something new like that but in the meantime my original Canon Selphy printer just keeps on chrugging. I have two backups for it now as I am sure it will fail at some point but I am amazed at how reliable its been for the small amount of money it cost.