I've been test-driving this now for the last couple of months, with the NIA 24 Skin Strengthening Complex. A kindly acquaintance sent me a box of goodies to try for sunspots, including the last third of a tube of this plus one full tube that I am just about to open. My skin DOES look somewhat better and there's been a teeny bit of fading so far, but more right now in the improvement of texture so far. The NIA 24 is very nice, and the cream feels really good going on. I didn't notice any flushing from this, and only one or two break-outs in the first week - after that, none. Sometimes I get a little dry - when that happens, I apply some of my own shea butter cream to drier areas, very simple and soothing. On their website they say when beginning this product one might experience a bit of flushing, a little breaking out that subsides very quickly, and dryness. I love the fact that the Strengthening Cream is not highly-fragranced either(just a slight scent which does not irritate my skin). I've been alternating this with some Retin-A as well, which I slowly introduced over a 2-month period without getting irritated, which is saying something for me with my skin!
Usually, and I know this from extensive research and having had medical spa consultations, the hydroquinone plus Retin-A combo is the gold standard for addressing hyperpigmentation from sun damage, and while that indeed does work within just a few months, it can be too aggressive for some folks. This is why it's great that there are some alternatives, but it will take longer for those to work as they are less aggressive. Better for more delicate skins though!