How do I judge print quality?
The cardinal rule of purchasing a printer is to print before you pay. Otherwise, there's no surefire way to tell exactly how text and images will appear. Fortunately, many retail stores let you print demonstration pages to get a feel for the output quality.
Compared to the original, the colors should be accurate, pleasing, and well balanced. Colors should be vivid but not oversaturated. Look at a monochrome photo under fluorescent light, incandescent light, and daylight. How badly does the color cast change from one light to another (called metamerism)? Be sure to look for inconsistencies across different paper types and print resolutions.
Is the output sufficiently sharp? Any jaggies? If you see problems, do you have any theories about what's going on? Does the lack of sharpness have to do with printhead or color misregistration?
Can you see detail in highlight and shadow areas, or are they rendered as flat or with no color? Does the printout look muddy or low contrast?
Do you see any banding? How about evidence of a clogged nozzle? Excessive dot gain? Any other weird stuff going on?