This is the entry-level version from Canon. Features a much improved focusing system over the original and has also added a swiveling screen.
The image quality is no different than what the more expensive models offer.
I'm a big fan of simple and high quality and this would be it.
I normally favor prime lenses for their arguably better image quality, but the versatility of this ultra-wide-angle is a very acceptable compromise (with more than adequate image quality nonetheless).
f/4 is probably as low as you'll ever need to go in this range and image stabilization can be nice unless on a tripod.
50mm, on full-frame, is a little wider than what the eye sees.
I agonized a lot over which 50mm lens to get and this is the one. It's really a very special lens that has it all - sharpness, "that special look" and lives on my camera unless I have a wide-angle or telephoto need. Love it; a lot.
A good way to achieve "that special look"; with the distance allowed by this focal length creating a very natural/non-distorted result. Universally recognized as among the best.
IS isn't really needed in most cases as long as you keep your shutter speed around 1/160 or faster.
It's a tough call between this and the 400mm 5.6, but this lens will be more useful overall. Very similar to the 200mm f/2.8 on a crop sensor with the added bonus of IS.
IS won't matter with faster shutter speeds, but may when slower than 1/320. When image quality is your #1 priority.
This lens is overwhelming versatile and offers remarkable image quality.
f/4.5 at 100mm isn't great, but since the DOF decreases with an increase in focal length f/5.6 is pretty good at 400mm.
I generally like my prime lenses, but can't get past the usefulness of this lens.
My personal choice.