Too inconsistent to be worth much.
CRAP
Cannot pick up clear temp differences
I tested the app with two banks of fluorescent tubes, each was clearly either daylight or a much warmer color. If I could upload a photo, you would easily see the difference. Yet this app rated them at essentially the same degrees Kelvin, 5150 (actual: 7 degrees different).
Maybe the eye and camera is very sensitive to color shifts and consequently it's too much to ask of an inexpensive app to resolve the difference. But using this app to chose replacement bulbs in a home or office would give unreliable results in matching sources.