I think that the color here is a little too understated for the current challenge. Boosting the saturation on the rainbow would make this a much better "Burst of Color".
A lucky capture. Still, I find this rather drab. The color doesn't make quite enough of an impact against the dull sky and the trees. The roofs should have been cropped out.
Great answer to the challenge. I like the feel and emotive quality of this shot. Maybe a tighter shot or more corp to bring the rainbow closer would have helped? Just my humble opinion, nice shot nonetheless