Meh....
You've a couple of issues. Looks like a couple of your frames were not as sharp as they should be and it shows with blur in the trees. Depth of field looks a bit short to me too, like it was shot wide open and you've lost a bit of sharpness to that too. Looks like there's also a bit of mild barrel distortion in the image as well. From your Exif data it seems this was shot at 18mm which is very wide for a pano. One of the great things about shooting in a panoramic format is it enables you to shoot at a longer focal length than you otherwise would be able to so you can retain the compression of the longer focal lengths but still keep the wide view. So it seems to me you might have been able to move back a bit and shot at a longer focal length which would have given the shed a bit more impact. I like the vingette wich is not too strong IMO.
Composition is a bit static and central, but the main issue for me is that the lighting is flat and even. For this shot to really work you need to get there when the shed is lit nice with some drama to it. I could totally see this as a spooky shed emerging from the darkness of the trees but the lighting in this shot just isn't right for that.