Buy for baby, keep for life
10/10 would recommend. The quality is excellent, the pattern is pleasing to look at (especially important in a room where we're spending so much time actively sitting on the floor), and the mat will work from newborn through toddler and likely beyond which makes it a cost effective commitment.
Given their strict return policy, I would just recommend triple checking your measurements before ordering (I placed books where the four corners would be so I could see what the mat size would look like). But unless the mat didn't physically fit in the space - or there was a defect - I can't imagine any reason to return it.