the building isn't very sharp, overall lack of contrast and there is a bit of strangnest going on between the clouds and the tree line.
clouds are one of those difficult items to control with this process.
the contrast can be tweaked after the merging of images, sharpness needs to be done at the time of the shot. Use a tripod and mirror lock up for increased sharpness.
For your first attempt it isn't as bad as my comments
As for compositon, i would place the building off center and reduce the amount of grass in the foreground.
At the size you have posted the bricks and roofing shingles forms moire patterns. These would go away if the pic was larger or smaller. Preferably larger. My only complaint with the image is the nuclear yellow green grass. Drop the yellow and up the cyan. And all is well.
It's a lovely building !! I'd maybe crop it a little, and remove some of the grass from the foreground , and concentrate on the building, tree and sky. It looks like it has been shot from slightly different angles and the photos layered and merged to make the image. I'm not sure though, because all of the photo would have that effect, where as it is just the building ??? I'm slightly puzzled myself