Very slight wobble at maximum zoom. It's a rather controversial lens. Excellent range for a walk about, and decent performance - proving you get a good one, some are reported to be a bit soft - but slow, indifferent build quality, and serious distortion at the wide end. This can be fixed in post processing, but it's a nuisance.
I got mine as part of a kit, and planned to sell it and buy something else, but I ended up keeping it. It was very overpriced when it first came out but you can find them for a lot less now. I'm going to replace it with the 17 - 55mm f2.8 when I can afford to, which isn't going to be any time soon, but even that isn't very well built for the price.