I'm giving you a low score because i see too much noise on this photo. The idea of using a rainbow for the theme Twisted is great, but the colors of this rainbow are weak and i think the sky didn't help you on that moment. I like your idea and i'm sure you can do it better!
Lots of grainy noise in this. This has the appearance of a severely cropped image. Some noise reduction might have helped a little, but when cropping that close, it's not a full fix. I think you just enlarged too much.
I think shooting rainbows are hard for a variety of reasons. The lines can look so thin in the big sky and sometimes the colors are hard to see. This photo meets the challenge though.
Apart from the strong clouds in the top right part of the picture, the picture lacks impact. The foreground detracts from the curve of the rainbow. Perhaps consider a more dramatic foreground.