Composition - There are some wonderful colors in this photo. The richness of the purple is very warm and springy. (I'm glad you used the color in the title as I'm color blind and have a heck of a time with blue and purple!) I think the part of this photo I like the best is the tree in the middle. It sort of divides the photo in 2 halves. The thing about this photo I don't like is the unevenness of the light throughout the photo. But overall I think this is a very nice photo.
Technique - This is a very well taken photo under these circumstances. The unevenness of the lighting makes it tricky to get the exposure just right, at the happy medium. The color would've shown up better if it were exposed just a little longer, but it definitely works as is.
Overall - I gave this photo a 7. I think its a pretty good photo with some great color. It is a good photo for this challenge. This is a nice pic. Good luck in future challenges. - Inspzil