Rotto , I like my 18-200vr very much and I've been writing about it in many threads, Thom hogan has a good report on this lens at
http://www.bythom.com
amongst other professionals, I read lots of reviews and comments by professionals and members over here and tried a couple before buying mine ,
I think , most negative comments have more to do with the fact that people expected this lens to be a 70-200Vr lens IQ and capability at a range of a f2.8 at a 18-200 range so they will never need another lens,
Of course its not like that , This lens like almost any other lens is a compromise from the perfect do it all lens , but for me anyway, this is a lens that can do 50% of my shootings, Now, that is fantastic, If you read many comments here you will find that many users of the 70-200Vr who praise this lens , and quite justifiably , as a legend , only use it 5% of the time ....
Remember that lenses are just tools ,, and what is important , well, for me anyway, is conveying a message ,with, of course optimal IQ as possible . This lens is (18-200VR) is , I agree with Ken's words : " a miracle" I just complement it with some primes. This lens is very sharp at the center even wide open , which is useful in some instances - I never got this sharpness with good lenses such as the 35-70 or even the 28-70 or 80-200. Its OOF -bokeh is not ideal for a top class IQ portrait for example the 70-200Vr offers much better OOF bokeh or the 85/1.4 is much better, BTW also the 85 ,althouhg an excellent lens, doesnt have the same quality bokeh (for portaits) as the 70-200 or the 85.1.4 for that matter .
The 18-200 is great if you want good IQ at 2 , or even perfect 3 stops down images for edge to edge sharpness , good contrast and color,
--
avis
http://www.pbase.com/avistar/avi_s_photographic_world
Nikon D70, 50/1.4, 105/2.8, 18-200VR SB600, SB800
Gitzo 1228, and 1226 ,