My firsthand report.
Tried the service on 10 different domains.
Most of the keywords weren't English, the English keywords seems to have improved rank quickly.
This weekend I noticed one of keywords shot to #11 on Google for a keyword with 80,000,000 search results. Now that's good. The other keywords didn't go up yet but the one that did was a domain that had age on it. The others were never developed.
So this may work really well for older domains.