atlrus - 7:35 pm on Dec 30, 2012 (gmt 0)
One could never know if the tool works, since it' not in a closed system.
Case in point, I had a website penalized (and got the unnatural links messages), but I said screw Google and did nothing - my website is almost fully recovered, "unnatural links" and all. So if you used the tool and your website recovered for some other reason, it's only natural (yet wrong) to assume that you recovered thanks to the tool.
Best way to look at this tool (or any other tool Google offers) is by asking yourself "Would Google really give webmasters a tool that would manipulate both the algo and results?"...