First, this is an image captured from the fifth floor of a building. We took this picture through a window glass so the light was dim. However, the panorama is good because there are many details so the feature matcher can do a great job.
The following screenshot is an image captured in the evening on a balcony. The region on the top-left corner of the panorama is bad since this only contains a blank wall and the sky. Therefore, there were too little features to compare between images. Hence, the final panorama is not perfect in this region.