What I see
A vertical bank of Gaudí stained glass, the color shifting from gold at the crown to deep red toward the floor, with saint names lettered into the small roundels. It reads as a study in color and structure rather than a devotional scene, and the register works because the photographer let the architecture do the composing.
What's working
Color gradient. The shift from lemon-yellow at the oculus down through someone and into blood-red in the lower panels is the frame's engine — it gives the eye a direction to travel even though the subject itself never moves. That gradient is intrinsic to the glass design, but exposing to protect it, rather than letting the reds clip or the yellows wash pale, was the photographer's job and it's done cleanly.
Black stone against saturated glass. Crushing the surrounding tracery and stonework to near-black isolates each pane like a lit cell, which is what makes the color read as intensely as it does. There's no ambient fill diluting the panels — the contrast is total, and it's what separates this from a flatter documentary shot of the same window.
Mirror symmetry. The two window banks split by the dark central spine give the frame a stable, almost heraldic order, echoed by the fan of the top oculus. That order keeps sixteen small panels from turning into visual noise.
What's not
Bottom crop. The lowest bank of arched windows is cut close to its base, so the rhythm established by the two rows above doesn't get to resolve — the eye reaches the bottom of the frame mid-form rather than at a clean stop. A small reframe, backing up or lowering the crop by roughly 5-8% at the bottom edge, would let that last row land on a natural stone break instead of an arbitrary one.