Sick is strongest with forum profiles across various platforms, although it will support bookmakring, articles, indexing work, and a few others. It's a tool, and like most tools, can be used appropriately and inappropriately.
With sick you can either purchase "packets" of platforms or harvest (think Scrapebox) your own targets and put them into lists. The software uses proxies to go out and register at these sites. Wait a day or two, use the software to activate all the links that arrive via email, and then you are set to start building links. It can and will build large amounts of profile links fast (although it's not as strong as Xrumer). Anchor text and target URL's can be rotated.
Does it work? It use to work extremely well, but is far less effective now. I wouldn't use it on a money site these days, but it still works well in moderation for 2nd or 3rd tier links.