I'm surprised nobody has posted a review of this lens after more than 12 months of being listed, so I thought I'd go first.
I purchased this lens, after reading many reviews and looking and hundreds of sample images, to replace my Tamron 18-270mm VC (which was a very disappointing lens in my experience, hence considering the purchase of the 16-300mm very carefully).
I'm pleased to say my experience with the newest lens is much more positive - for the most part.
IQ is substantially better than the 18-270 and, considering the 16X zoom range, quite good overall (not as good as my L series lenses, obviously, but it's horses for courses).
The downside - my lens had a serious issue where, when the VC engaged, the image shifted substantially in the viewfinder (hence my lower rating for build quality) and kept jumping backwards and forwards... by as much as 15% of the field of view.
I returned it for repairs and I'm pleased to say all is good now.