"Let Love Rule" was from Kravitz debut album of the same name, and it became his first charting single, at #89. The album peaked at #61 and remains (as of this writing), Kravitz' only non-top 40 album of his entire career. Interestingly, Kravitz has only had 4 top 40 singles, and "Are You Gonna Go My Way" was not one of them (it somehow failed to break the top 100 in the U.S.).
The video for "Let Love Rule" was directed by Lenny Kravitz' then-wife, Lisa Bonet (they divorced in 1993). The home movie feel and use of kids was highly effective in my view and presented Kravitz as a modern hippie -- something that he didn't really shake until the success of 1993's "Are You Gonna Go My Way."
While "Let Love Rule" was a modest hit in the U.S., it really launched Kravitz in Europe, and he remains the rare artist who is probably more successful outside of his home country.
Cool trivia fact: The video for "Let Love Rule" was nominated for MTV's best new artist award, but he didn't win -- Michael Penn did for "No Myth," which was featured on ERV in November 2012.