I've been taking panoramic photos for a couple of years now but until recently have not tried any of the software available for the mac. I decided to give a couple a try last night and came out with mixed results. As input, I used five source files taken by manually panning myself from the top of a hill at a park near my home.
DoubleTake's UI is really simple, you drag a couple of images onto the lower pane and DoubleTake immediately aligns the images, crops and offers a preview. I wanted to change some of the colors but the HUD didn't seem to allow modification, perhaps this is the result of being a trial.
If you look closely, the color of the grass on the left of the image is different from the rest though the photos were taken within seconds of each other.
Calico is based on AutoStitch technology and also uses a simple drag-and-drop interface. The primary difference I found in my quick trial was it didn't crop automatically.
The color was much more uniform with Calico but if you look at the tree by the rock it looks superimposed and blurry. This is odd because the input photos didn't overlap at this point so I'm not sure why this happened.
Both did a pretty good job stitching together the images but neither was perfect. I'm leaning towards DoubleTake but haven't made a final decision either way. I'm open to suggestions for alternatives.