I have one, and have usde it on my D60, D5200, and D7100. For what it is and how much it's available for, it's not bad, and I do enjoy using it. While it's not a true macro lens, the feature has actually come in fairly handy for me once in a while too.
Around 200mm and above, the images do tend to show a bit on the softer side [but that's when I just change my style to suit it haha ;)].
I would say go for it, depending on price. I paid about $190 (CDN) before tax and do not regret it.
There are a number of my photos taken with this lens uploaded on my account if you'd like to see exampled. Just look at all the photos that say "70.0-300.0 mm f/4.0-5.6". They're all taken with the Sigma 70.0-300.0 mm f/4.0-5.6 DG Macro (no APO or OS).