I have a mid-price Samsung and did not really see issues with distortion and much has to do with the care you take to compose. It is all about composition, angle held relative to subject, and even lighting. The phone handles the focus and autoexposure fine, The goal is an image better than 90% of pics of stamps taken with a phone.
I experimented yesterday with a usb attached phone using file transfer and in the end I would need a dedicated phone for high production work. I did not like the phone locking (need to disable that), and ergonomics of reaching over to take the picture on a touch screen above me. If USB was disconnected I had to deal with entering the password to give permission to attach. I plan to try the Link to windows. I did mount my DSLR and there was a simplicity to attachment and actuating shutter (does not tie up my phone.)
This was without any supplemental light using 2x zoom feature (likely optical zoom). This phone is not noted for any great camera.
