Good all-around; do not expect "pro" results

Being the first to review the lens here puts some responsibility on my shoulders :)

I've used this lens for the past month or so in a variety of conditions on my D70s. Images come-out with good color and contrast as they tend to with most good quality Nikon glass. My comparisons are based on the following lenses that I either own or used to own: 50mm AF-D f/1.4 (Japan version), 80-400 VR, 70-210 AF-D, 18-70 "kit" lens, 70-300 ED (all Nikons) and the 70-300mm DG from Sigma.

The Good: VR, autofocus speed and acuracy, center sharpness, contrast, relatively compact.

The Bad: Light fall-off, corner softness, slow (at f/5.6 max at tele), distortion, cost (at $669 to $899 street prices I've seen at retailers recently).

The Verdict: it is a keeper as there is nothing quite like it on the market for DSLR (there are plenty of alternatives in the "mega zoom" point and shoot arena).

Is it for you: If ultimate image quality edge to edge and without much post processing is a must for you, this lens will trouble you with its distorsion, corner softness and light fall off. It is however a very capable all around zoom that will please most casual shooters. The more demanding users should still wish to keep their "pro" lenses in the bag for these special situations when they have to have it all! Could it replace your "kit" lens and your 28-200G or similar - for most practical purposes, yes. Is the premium over 18-200 Sigma or Tamron justified? Yes, IMO as the VR will save you many shots and the optical quality is on par or better (based on others impressions, I do not own these lenses). Finally, a Tokina 12-24 & Nikon 55-200mm may give you better coverage and avoid some of the distortion/fall-off issues for about the same price (no VR though). And keep (or get if you do not own one) your fast 50mm or 35mm lens - it comes handy when you can't use flash in dark environments where the VR is not of much use when subjects move and you can't attain shutter speeds above what you need with this "slow" lens.

Here are some more details:

VR is very nice. I had the 80-400 VR for some time and the new VR-II in the 18-200 seems to indeed work a bit better. It is useful not only to let you shoot at lower speeds wide open (maximize the aperture), but also to close-down the lens to increase the dept of field for more creative control. I can't overstate the importance of VR for a walk-around lens like this one. Even at the wider end it will save you from camera shake in many situations and can produce useful results quite reliably down to 1/10s at 200mm (just don't expect tack sharp 20x30" prints from them; but perfectly good for web or 4x6")

Sharpness is pretty good, except in the corners where there is visible softness, especially below f/8 but still present at all apertures and focal lengths. Center sharpness is marginally better than the 18-70 Nikkor kit lens (based on my own tests as well as the general consensus of new 18-200 owners who sold their kit lenses, myself included).

Light fall-off in the corners is very visible below f/8 and almost non-existent above that. The bad thing is that Nikon Capture 4.3.2 cannot fully compensate for it. The fall off (vignetting) is not worse than with the kit lens, just apparently has different characteristics and the software is not calibrated for it. There are other software such as the "free" PTLens plugin for Photoshop (or Photoshop Elements, which I use) that can pretty much completely eliminate the fall off.

Distortion is probably the weakest point of this lens. At 18mm it has barrel distortion similar to the kit lens, at around 24mm it has almost none. Above about 40mm it has very visible pin cushion distortion all the way to 200mm and it is worst at 60-100 as far as I can tell. Again, use PTLens or a similar tool calibrated for this lens to correct. Unfortunately, it is not possible to fully correct the distortion and this may remain visible in certain shots with straight lines running close and parallel to the frame edges. If the scene does not have straight lines you can ignore the distortion such as in landscapes or people shots. Otherwise it may bother you. In comparison, the kit lens has practically no distortion towards its long end.

The zoom ring felt terrible when I first bought the lens. It was very stiff, felt rough as if there was fine sand paper grinding the guts of the lens. It was (and still is) unevenly stiff across the focal length. It smoothed-out considerably during the first few days of use and now feels OK (except that it still is uneven across the zoom range). There is slight zoom creep at certain focal lengths mostly b/w 24 and 136mm if the lens is held steady upright or down vertically. It does not show if I carry the camera on my neck/shoulder as in this position the lens is at about 45 degree (not vertical) and the zoom is stiff enough to prevent creep in this situation.

Manual focus is not good - stiff with about 1mm play in each direction before actually engaging the focus mechanism. this makes it tricky to get fine manual focus. I tried another sample in the store and it felt every bit the same as mine (focus, zoom stiffness etc.)

Autofocus speed is fast, probably faster than the kit lens. In my own subjective experience I feel the 18-200 VR hunts less and acquires and keeps focus better than the kit lens, though I have not tested specifically for this.

There is very little flare and ghosting when shooting against light sources. A multi-coated filter will not significantly increase this where a non-multi-coated will (my own tests confirm this). Flare/ghosting is practically a non-issue with this zoom.

Check my sample photos and tests at my PBase Gallery for this lens http://www.pbase.com/kocho/nikkor_nikon_18200mm_vr. Visit Nikonians.org for great advise and DPReview for the same plus lots of rambling. Please, ask your questions at these two forums as I am unlikely to answer any on this site here.