I used Sharkey's after TTC for about a year. I conceived a year later. The thing that makes me believe the herbs are helpful, is the temp chart. I could see month by month how my temps were changing to make my cycle more balanced.
I've always been a believer in natural remedies, but I admit sometimes it's hard to tell if they have made a difference, especially since they are usually long-term solutions - no quick fixes. But the balancing of your cycle, as indicated by temp, is visual proof (IMHO) that the herbs are having an effect.
I'd recommend them anyday.