24mm lenses are the entry into ultra-wide angle photography and this lens is the ideal starting point.  It is extremely sharp and offers superior correction of linear distortion, and its f/2.8 aperture makes it easy to use with slow, fine-grain films or in low light. It focuses as close as 10 inches (25cm), and for many photographers gives the ideal combination of a wide-angle “look” without excessive perspective distortion.

Reviews

Canon EF 24mm f/2.8 Lens Review by the-digital-picture.com

If you need very decent quality images from a 24mm focal length lens, do not have the budget for the Canon EF 24mm f/1.4 L II USM Lens and do not need the versatility of a zoom for your particular purpose, the Canon EF 24mm f/2.8 Lens may be the right choice for you. With its light weight and compact design, the Canon EF 24mm f/2.8 Lens is a convenient lens to pack along everywhere you go. And then there will always be a wide angle lens at your disposal.

Canon EF 24mm f/2.8 – Review by photozone.de

At the optimal focus distances the EF 24mm f/2.8 is an excellent performer capable to deliver images as sharp as it gets on an 8MP APS-C DSLR. For most situations this is generally true but residual spherical aberration can be a problem at close-focus distances (as explained in the MTF chapter above). Other than that vignetting is a little on the high side at f/2.8 but no issue beyond and the slight barrel distortions are usually very acceptable as well. The construction quality is decent though not stellar.
So at the end of the day it remains an excellent lens … with a little bug.