Mine gets carried around in the case that Sigma provide (by my wife if I can persuade her to carry it!). While I'm sure my camera body and the lens's own mount are strong enough to bear the strain of being carried around together, I tend not to use it in that way.
Issues? Well, it's not light! Can be a bit slow picking up a moving target against a cluttered background. F/6.3 at the long end, so you might need higher ISOs - not a problem with my D700. Ideally needs to be stopped down a little to improve sharpness which can cause even slower shutter speeds. OS works well, allowing handholding at way slower speeds than you'd expect. Zoom creeps out if it's carried pointing down (using the zoom lock stops that but is easily forgotten if a shot appears from nowhere!).