A very strong impact for me. The orange and blue color works really well. There is plenty of detail in the saguaro and enough light in that part of the sky to define it - I think the shot would lose some of its strength and mystery were it better lit. The composition is very strong as well with the cactus well ballanced by the negative space. I like the barely seen bush that anchors the lower left.

This is one that I would love to see printed.