Your idea is wonderful. It is the execution that could use a tad bit of help. yOu could improve on composition by using the rule of thirds for the sun. For some reason the color does not seem right.
i think levels would help out here. the sky is a bit gray, and the hill is a dark gray. adjusting the levels to get some black in the hill and lighter sky might help.
Good eye for this sunset! A bit more contrast--darker darks, for instance, might help the image pop even more by providing darker tones to contrast the sun's lighter ones?