The 24-105mm is certainly not perfect; a Zoom is ultimately always a compromise, and just purists are likely to interfere in the relatively large focal length range. The light intensity is at a maximum aperture of f / 4, for example not outstanding, on the other hand, however, applies throughout the entire zoom range; in low light, this shortcoming can also make up for by the good functioning optical Image Stabilizer at least partially again. Who comparable L lens with higher brightness wishes (for example, the 24-70mm f / 2.8), also has to reach much deeper into their pockets.
Another (small) complaint: When using on Crop cameras it unfortunately lacks a bit in wide angle - who flirts with the purchase of this lens, but are likely to be aware, and who it bothers, must alternatively grab just a superzoom or set to complement a wide-angle lens. A positive side effect occur at Crop cameras However, unlike full-format cameras practically no problems with vignetting on, and by the extension factor of 1.6 in my EOS 20D to a maximum telephoto focal length of 170mm results in at least almost.
Overall, I never regretted buying this lens at any time. As you would expect from Canon L lenses, this zoom is very well made and performed solidly and has pleasant common zoom and focusing rings. The fact that this also leads to a relatively high weight, I take it gladly accept. With the image quality I am very satisfied, and this can also be displayed on full see. The ultrasonic motor quiet as a whisper, reliable and super fast, and you can manually adjust the sharpness in autofocus mode at any time, and since this objective, unlike the EF-S lenses is also full format compatible, it can be necessary even on old EOS-Analog housings or use of Canon's full-frame DSLRs.
This lens provides me with its high image quality and the great flexibility and is more than satisfied my ideal of a high-quality travel and reportage grade "Always Draufs" very close. While it's not cheap, but good value in the most literal sense.