Also this type of a lens is used for creative pictures from portrait to travel photography, is it more a specialist lens for landscape photographers. This lens is so far that it is suitable for landscapes. Watch a DVD or Blu-ray, than compare it with a super-wide-angle lens anamorphic wide picture. You will see what I think about.
This lens offers a focal length down to 12 mm – I prefer a 16-35 mm 1:4. On lenses with a smaller focal length of 12mm we talk about fisheye lenses, these lenses are not suitable for serious landscape pictures. If you are using a full-frame DSLR you can work with lenses they are made for this use (f. e. my Canon 16-35 mm), this is making a more width picture than with a standard DSLRS with APS-C-Sensor. Especially with full-frame cameras you will see the explicit improvement of the width in the picture if you are using a super-width-angle lens. As well you can use your APS-C-Sensor DSLR but the improvement of the width isn’t that much like with a full-frame.
If you really want to try it and see the difference between the APS-C and the full-frame, rent a full-frame camera or ask someone who have one to borrow it to you. Have fun and enjoy the difference between the two formats.