To quote the homepage:
"Intelligent panorama finder - Simply drop a folder full of your vacation photos into Calico and Calico will figure out which photographs should be made into panoramas and which photographs are single images."
Usage is indeed very simple, in this example i just use some pictures i made out of my office window.
Pressing "Load" will open a file dialog where you can select the photos you want to use for your panorama.
Now you can do some adjustments, but most times you can just press "Align"...
...which, after a few seconds, gives you a preview of the panorama.
Now you can export the picture in various formats and sizes.
And here is the result:
As you see its quite simple and fast to make impressive panoramas, in this post i only covered Calico v1, but if you buy it you get v2 as well which gives you more customizations and options to play around with.
I prefer v1 cause its simple, easy to use and gives fast results.
PS: here are the source images