Here’s a very good example of a helpful review. I’ve always been wary of zoom lenses, because of the optical compromises implicit in them, but I’d heard good things about the Nikkor 18-200mm DX. So I went to dpreview.com and found a detached and informative assessment. Here’s the overall verdict:

Just occasionally, the old cliches are still the best, and with the 18-200mm VR the phrase ‘jack of all trades, master of none’ springs immediately to mind. It’s a lens which delivers somewhat flawed results over its entire zoom range; where it’s sharp, it has heavy distortion, and when that distortion comes under control at the long end, it loses sharpness. Its close-up performance is reasonable, but not spectacular, and overall it will likely be outperformed optically by a cheaper combination of standard and telephoto zooms. So for a certain type of photographer interested mainly in absolute image quality, this may well cause it to be regarded as nothing more than an expensive snapshot lens.

But to dismiss the 18-200mm VR based purely on its optical quality is to miss the point quite fundamentally. The whole idea of such a lens is to allow the photographer to travel light and never miss a shot while changing lenses, or indeed not to have to risk water or dust entering the camera in adverse conditions. So what you do get for your money is a hugely flexible zoom range which can handle the vast majority of photographic opportunities, coupled with excellent autofocus and vibration reduction systems. And all of this is wrapped up in a relatively compact package, with build quality which feels solid without being excessively heavy. It really is a lens you can leave on your camera all day long and scarcely miss a shot, and it has to be said, this makes it a lot of fun to use.

So when all is said and done, we have to understand that superzooms are essentially about making some optical compromises to provide the broadest possible range in a single lens, and it’s up to each individual to decide whether those compromises are acceptable. I wouldn’t recommend the 18-200mm to someone whose primary interests were either architecture or wildlife, for example, but for the photographer who wants to shoot a little bit of everything and not have to change lenses, it’s more than fit for purpose. Ultimately this is probably as good a superzoom as money can buy, so as long as its limitations are recognised and understood, it has to be recommended.