I love Popsicolor! It’s the latest tool in my little iPhone artbox. I think it provides beautiful results given the right input file. It is a bit picky! I find that† it’s easier on the program, and lends you more control if you make the photo black and white and control the levels before you hand it over to Popsicolor.
I think these would make some fun prints!† Here are the Marriott Marquis and a rack of ties that have been run through the process.