When evaluating photos, it's important to consider both the technical and visual quality. The visual quality is influenced by various factors, such as the quality of the camera used to capture the photo, the sharpness of the focus, color representation, brightness, and contrast of the image.
To check if the photo is sharp enough, you can zoom in extensively on the original photo (not in the IXXI editor, but on your own computer). When you zoom in (which is also what happens when you print your photo on an IXXI), you'll see all the small imperfections of the photo very clearly. Unfortunately, the visual quality cannot be measured technically in the editor, which is why it's important to check this yourself beforehand.