Glad to see som positive feedback
I can only agree with wout89 here, (especially the golden ring is a must
I have not yet tried it out, read Ken Rockwells review and he prefered the 28-300 just because it was more bang for the buck and a wider zoom range. It is bang on sharp through out and colors should be great, it has some distortion throughout the entire range, that was it's only major flaw, otherwise a great lens according to Ken R.
I have also noticed that many professionals prefer a lens like this one, for example the equivalent Canon lens 24-105 f/4 is a very popular so I think the 24-120 is a very good allround lens to mount at most times.
As an allround zoom I think f/4 is fairly ok, not f/2.8 but lest just say that in low light or for a high demanding portrait I should use a prime anyway so if not the aperture is super big I can still live with that.
Also I am not appealed to buy lets say the 28-300 because on the tele end I have understood that anything but f/2.8 or maybe f/4 limits your oppurtunities, for example to shoot sports. Therefore I am going to need a dedcated large apertue tele lens anyway and am not in need of a super zoom, thats why I prefer this lens.
I think that zooms are sometimes underestimated, today they are very sharp and very useful, and the "sharpness" of them are sufficient enough for most situations I think, it's the aperture that limits them...