9 out of 10 points and recommendedLightweight, good image quality (for the price)Cheap built (so not a show off lens)
First, I would like to say that I second ssj_george findings about the IS kicking in with a slight delay. It seems that it kicks in delayed and stops with a delay as well. Perhaps has slower movement sampling rate and thus needs more time to figure out what kind of movement to compensate for, something along these lines. Once you are aware of it, you can work with it.reviewed March 10th, 2011 (purchased for $255)
Onto the lens, for the price you simply cannot expect L quality.I would not even compare an L with this lens as there is no point in doing so from the start.
For what it is, the quality is surprisingly good from wide to about 200mm. At 250mm you can see some softening but not enough to be a problem (for serious work you would be getting a different lens anyway).
In good light, this performs well, with fast focus (again, seeing this through the price and what it is). However, we both know that in demanding situations with low light, things are never easy and this lens is not going to work for demanding scenarios of any kind.
I bought it for fun and I am having lots of fun with it, on a 1.6x crop body it goes to 400mm equivalent with decent results, for the price you can't get any better than this.
Build quality is cheap but who cares, it works just as good and you won't be needing minute focus/zoom adjustments to the point to be limited by the plastic-o-cheap build :) While the main body looks OK, the extending part looks like a painted toilet paper core :P
Okay, in the end let me say this: With this lens the pictures are way better than with any point and shoot mega zooms out there, so you get the idea.
Buying it for any serious work must be done only if you expect very good lighting always. In the end photography skills are what will make your picture.
Best buy for a fun lens with some reach. Set your expectations right and you won't have any disappointments.