What do you like best?
HARO is a great tool to introduce you to reporters who are already writing stories and need sources to quote or feature in them. It is completely free to use, as both a source, and a reporter, and it's the first tool I recommend to my students and clients who are just starting out with PR and publicity.
What do you dislike?
It sends out three emails a day, and it can be a lot, and many people who are on the west coast miss out on the morning queries. Both but of those are very minor annoyances, especially considering that it is a free service. Also, because it is 'reactive' - you are responding to the queries for stories that are already being written - you don't have a lot of options to influence the content or angle of the story.
Recommendations to others considering the product
If you're just getting started, check out The Quick-Start Guide to Getting HARO, to learn how to get the best results, and impress reporters, at melaniedowney.com
What business problems are you solving with the product? What benefits have you realized?
It's an easy way to gain media coverage, especially for many of my PR/publicity students, who are just starting out either in their businesses, or in public relations outreach. In most cases, they are able to get quoted in articles in just a few weeks.