Yes, I have used Motif a couple of times with good results.
When you click on the Checkout button you will get a notification if there are issues with any of your photos. Check out the photos marked in the upper right corner with an exclamation point inside a triangle, and click on the triangle. It will tell you if your photo is of too low a resolution that it won't print clearly. I have found that I can remove the warning triangle by exporting the photo from the Photos library onto my desktop and opening it in Preview. Then I select Tools/Adjust size and make sure that the long resolution number is at least 2500 if the original number was smaller. I also adjust the dpi to 300 if it is 72 or some other lower number. Then I drag the photo back into Photos and into the Motif photo book, and insert it into the project in place of the old photo. That gets rid of the warning notification triangle.
Sometimes choosing a smaller sized template display (like from full page to a smaller rectangle) will cure it as well. Zoomed photos, of course, always have resolution issues. Also, if the photo itself wasn't good quality to begin with it won't print in good quality.
The photos can be edited by clicking on the photo in large view, and then clicking on the Edit button. The Photos app edit screen will open and you can adjust sharpness, definition, exposure, brightness, color and so on.
-- Rich