Every lens is specialized in one way or another - and the 18-200mm is no different. For me it was - or would be if I still had it - the ideal walkin'-'round, shootin'-stuff lens. Great when just walking out to do some "street" with nothing specific in mind. It has the versatility to allow one the freedom to pick a subject and capture a perfectly usable image. I may add a DX body, simply to be able to re-buy the lens. I do a lot of "street" and the D700 for all its wonders, is not the ideal street camera. The problem is that I need a bag of heavy lenses to do what the little 18-200mm accomplishes with just one.
Certainly, it would not be my first choice for epic landscapes or any sort of contemplative photography. That would call for a prime, or a gold-ring zoom like my 14-24mm f/2.8 which can match the quality of the primes it actually can replace. However, it is huge, heavy, vulnerable, expensive and attracts far too much attention. If Nikon were to come out with an f/4.5-5.6 version of equal quality, I would trade before nightfall.
However, for someone just getting started in photography, the 18-200mm is an excellent choice. It takes time to understand the flavour of focal lengths in order to buy wisely. There are "better" individual lenses at all the focal lengths covered by its zoom range, but for a beginner, it can be a costly lesson trying to find the ideal combination.
It is a lens well suited to learning. One can simply dial in the classic photojournalist's kit. Its 18mm on a DX camera is on the border between wide and super-wide, but wide enough to learn a lot about the nature of wide-angle lenses. At the other end, on a DX camera, 200mm is on the threshold of super-telephotos. Having VR at that focal length may increase the number of keepers substantially. As a lens on a family camera, it can well cover all occasions, special days, holiday travel and so on. For many, it may be the only lens needed - allowing one to use a DX camera much as a point and shoot. For the person becoming enthusiastic about photography itself, by the time one has reached its limit one will understand well enough to make the next lens purchase with full understanding of the problem the next lens will solve.
I agree, for the most part, the 35mm f/1.8 would be a good choice as a second lens. I would however recommend the f/1.8 50mm in preference to the f/1.4. First, it is measurably sharper to f/5.6 where the f/1.4 catches up, but does not pass. It is smaller, lighter and costs
MUCH less. Very fast lenses were great in film/AI-S days, since they made manual focusing much brighter, and one could more easily be assured that the spot you want is going to be in focus, no matter the aperture you are using. Now, autofocus works as well at f/5.6 as manual focus did at f/1.2.
Back then, every working photographer was well aware you
never shot wide-open unless there simply was not enough light to go to at least f/2.8. There were exceptions, that were specifically corrected for wide-aperture shooting, however, they were very expensive and useless in bright light. (Noct-Nikkor and Leica Noctilux) Now, with the great high-ISO capability of the top DX cameras and the incredible capability of the FX cameras, super-fast lenses are obsolete. I would be completely content to have a set of lenses for my D700 with maximum apertures of f/4.0. I know the sweet-spot apertures of all my lenses and shoot there in pretty much any light. It is extremely rare to ever shoot at maximum aperture when ISO25,600 produces completely usable results. For proof go to
Available Darkness
Walking around with an f/1.4 is great if you regard lenses as jewelery and want to intimidate the newbies. I love the 50mm f/1.8, but generally shoot at f/5.6 where it is brilliant, and never shoot below f/2.8. A 50mm f/4.0 of equal quality would get my full attention.
