Okay so as this is in the gallery section, I'd better post some pics!
First I should say, I'm not entirely certain my copy is in full working order. There's a couple of quirks with the focus that I'm not sure about - but I haven't used a third party AF lens in years so maybe it's just that. First impressions other than that: it's a beast. Big and quite heavy, but solid and feels well built. The image quality when AF works is very good - sharp at f/2.8-f/8 (not tried it at narrower apertures yet). For my purposes - close shots of easily-flushed insects and the odd dreamy flower - it seems ideal, as you'd expect.
Here's a hoverfly. Handheld focus stack, 5 shots at f/2.8, not quite at maximum magnification, natural light. A dandelion seedhead and cherry blossom, f/2.8. All moderately cropped.