For more on optical considerations, see Making Sharp Images.
My comments are aimed at full frame users. Cropped-frame DX users might find the 24-120 a reasonable choice for images ranging in quality from acceptable to very good, varying by focal length.
Versatility of focal length range and a slow maximum aperture are reluctant trade-offs for the gross distortion and mediocre sharpness over the far ends of the zoom range. On the other hand, those compromises might be perfectly fine for some shooters.
I’m a little uncomfortable judging this lens. On the one hand its 5X zoom range and VR are appealing, its mid-range performance is very good, yet the mid-range distortion and the performance at the telephoto end make it a very tough call. I prefer predictable performance, but it’s fair to say that users comfortable with those limitations could rate this lens much higher for their own use than I would for mine.
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