PC Magazine has reviewed the "Polaroid PoGo Instant Mobile Printer," a cellphone-sized device that uses special, proprietary paper that has the ink already baked in. Because it's so inherently superficial to begin with — nobody needs to print pictures to share them these days — I wasn't that peeved by the announced $150 price or the fact that you could only buy paper from Polaroid. But I did expect it to make nice little prints — something that it can't quite pull off, it seems.
Output quality is far from ideal, or even what you'd expect from your local drug store. Colors in more than half of my test photos were noticeably off, shifting some light colors to yellow, some shades of red to purple, and making some photos seem faded or washed out.
That said, however, quality that would be unacceptable in a 4 by 6 isn't necessarily unacceptable in a 2- by 3-inch photo that's meant for a wallet or for literally sticking on a refrigerator door, desktop monitor, scrap book, or school locker. I'd call the quality good enough for the intended purpose. It helps too that the photos are both water and scratch resistant. Cost per photo is currently as low as 33.3 cents if you buy them in packs of 30 sheets.